Joseph Mouallem

The Duo-Grid and Cubed-Sphere Grid Imprinting

Fri, 01 Dec 2023 00:00:00 +0000

Motivation

Addressing the challenge of running localized high-resolution simulations within a global model, the duo-grid imprints a finer mesh over a region of interest, reducing computational cost by an order of magnitude compared to traditional regridding approaches.

The problem: grid imprinting

The gnomonic cubed-sphere grid has excellent accuracy and uniformity, but the coordinates have a kink at the cube edges. In the halo region this kink leaves a visible imprint of the cube in the solution and requires special edge handling throughout the solver.

The Duo-Grid

To reduce grid imprinting, we implemented the novel Duo-Grid within FV3. The Duo-Grid remaps a cube face’s data from the neighboring face, moving it from the kinked locations to natural locations along great circle lines using 1D piecewise linear interpolation. A separate 2D interpolation algorithm fills the correct data at the eight corners of the cubed-sphere, which FV3’s 2D advection scheme requires.

C8 cubed-sphere grid with a three-cell halo. Left: “kinked” grid showing halo updated directly from the neighboring face. Right: “extended” grid for the forward face showing data remapped onto the extended grid. Note that the great circle coordinate lines extend from the compute domain into the grid halo without interruption..

Validation

The Duo-Grid was evaluated across a comprehensive suite of idealized test cases spanning both two-dimensional shallow-water dynamics and three-dimensional hydrostatic and non-hydrostatic flows. These tests were designed to assess the impact of the Duo-Grid on grid imprinting, numerical errors, and the overall behavior of the FV3 dynamical core.

The steady-state geostrophic balance test provides a direct assessment of cubed-sphere grid imprinting. When the flow is oriented perpendicular to the cubed-sphere edges, the conventional kinked grid produces errors aligned with the cube geometry. With the Duo-Grid, these grid-aligned errors are substantially reduced.

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Meridional velocity errors of the C48 steady state geostrophic balance flow with a flow oriented perpendicular to the cubed-sphere edges. Duo-Grid significantly reduces these errors.

The improvement extends to fully three-dimensional dynamics. In the baroclinic wave test, the Duo-Grid suppresses the development of cubed-sphere imprinting and errors in the southern hemisphere while maintaining the evolution of the solution over time.

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Time evolution of meridional winds in the three-dimensional baroclinic wave test, demonstrating the reduced cubed-sphere errors in the southern hemisphere with the Duo-Grid.

The Duo-Grid was further evaluated using a broad suite of standard idealized tests, including shallow-water steady-state geostrophic flow, the splash test, Rossby–Haurwitz wave, colliding modons, cosine-bell advection, and the three-dimensional non-hydrostatic baroclinic wave.

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Idealized test suite run on the Duo-Grid: shallow-water steady-state geostrophic flow, splash test, Rossby-Haurwitz wave, colliding modons, cosine bell advection, and the 3D non-hydrostatic baroclinic wave.

Across these tests, the Duo-Grid consistently reduces grid imprinting and numerical errors while preserving the accuracy and numerical characteristics of the original FV3 formulation.

Key results

Grid imprinting of the cubed sphere is greatly reduced in idealized tests and practically eliminated.
Duo-Grid decreases the growth rate of error norms in all cases compared to the kinked grid, up to one order of magnitude.
Order of accuracy of FV3’s horizontal discretization is conserved.
Dispersion and dissipation properties are identical to those of the original FV3 algorithm.
Edge handling code is eliminated -> significant performance gain in current/future GPU development
FV3’s robustness and accuracy have increased.

These results indicate a clear improvement in FV3’s robustness.

Reference

Mouallem, J., Harris, L., and Chen, X.: Implementation of the Novel Duo-Grid in GFDL’s FV3 Dynamical Core, Journal of Advances in Modeling Earth Systems, 15(12), 2023. https://doi.org/10.1029/2023MS003712

Multiple Same-Level and Telescoping Grid Nesting

Tue, 07 Jun 2022 00:00:00 +0000

Motivation

Multi-scale modeling often requires simulations at many different resolutions. This work shows how to couple coarse and fine domains within a single dynamical core, enabling cost-effective high-resolution forecasts of localized phenomena like hurricanes.

Overview

Two-way multiple same-level and telescoping grid nesting capabilities are implemented in FV3 using GFDL’s Flexible Modeling System (FMS).

A nest is an additional grid that zooms in over a region of interest to resolve the small-scale structures needed for better forecasts of localized weather events such as severe storms and hurricanes. A telescoping nest is a nest within a nest, allowing resolution to be refined progressively over the target region.

Nests can be used in both global and regional domains, and each level of the hierarchy can refine the parent resolution by an arbitrary factor.

A telescoping configuration refining a global ~13 km grid down to ~4.3 km, ~1.4 km and ~0.5 km over the region of interest.

Computational design

The nested grids run concurrently on different sets of processors and interact two-way with their parent grids. This provides more accurate results on both the nest and the parent, and reduces load imbalance between processors.

Availability

Starting from the FV3 public release of 2021, multiple same-level and telescoping nests are fully functional and available to the broader scientific community. This drastically improves overall forecast performance and opens the door to numerous research possibilities for scientists and meteorologists alike.

Reference

Mouallem, J., Harris, L., and Benson, R.: Multiple same-level and telescoping nesting in GFDL’s dynamical core, Geoscientific Model Development, 15(11), 4355-4371, 2022. https://doi.org/10.5194/gmd-15-4355-2022

SHiELD-LM4: Coupled Land-Atmosphere Modeling

Fri, 04 Sep 2026 00:00:00 +0000

What I developed

Implicit land-atmosphere coupling between SHiELD and LM4
Integration of the LM4 land component into the SHiELD framework
FMS coupling and exchange-grid infrastructure for conservative water and energy fluxes
High-resolution coupled hydrological simulations
The Hurricane Helene (2024) case study evaluating hydrological extremes

Motivation

Land-atmosphere interactions drive weather and climate extremes. This system integrates advanced atmospheric and land processes to capture how soil moisture, vegetation, and runoff feedback on regional weather patterns, advancing forecast skill for hydrological extremes.

Overview

We present a new high-resolution coupled atmosphere-land model, SHiELD-LM4, which integrates GFDL’s advanced atmospheric model (SHiELD) with the Geophysical Fluid Dynamics Laboratory Land Model (LM4) through the Flexible Modeling System (FMS) coupler. This coupled system enables accurate representation of land-atmosphere interactions, including soil moisture feedbacks, runoff generation, and hydrological extremes.

The model captures critical processes such as precipitation-driven runoff, soil water dynamics, and their impacts on atmospheric evolution during extreme weather events. High-resolution representation is essential for resolving the complex interactions between atmospheric convection and land surface hydrology.

Coupling Infrastructure

The SHiELD-LM4 model employs the Flexible Modeling System (FMS) coupler to facilitate bidirectional exchange between the atmospheric and land components. The exchange grid ensures accurate conservation of water and energy fluxes at the atmosphere-land interface.

Schematic of atmosphere (Atm), exchange grid (Xgrid), and land/ice components showing multi-level coupling infrastructure and flux exchange pathways.

Hurricane Helene (2024): Precipitation and Runoff

A key application of the coupled SHiELD-LM4 system is realistic simulation of extreme precipitation and its hydrological consequences during tropical cyclones. The animation below shows global precipitation and runoff during Hurricane Helene’s landfall, zoomed on the southeastern United States to reveal localized hydrological response.

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Global precipitation (mm/hr), surface runoff, and river discharge (kg/m³/s) during Hurricane Helene (2024). Zoomed panels show detailed runoff and river flow in the southeastern U.S. during landfall.

Soil Moisture and Land Surface Response

The coupling captures soil moisture evolution and its feedback to atmospheric conditions. The animation shows soil liquid water content evolution during an extreme precipitation event, with time series of observed vs. modeled soil moisture at multiple locations.

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Time series of soil liquid water content (kg/m³) at multiple observation sites during Hurricane Helene, illustrating the rapid soil water response to extreme precipitation and subsequent drainage.

Soil Column Interactions

The detailed representation of soil-atmosphere interactions is illustrated through the vertical exchange of water and energy between atmospheric columns and land model soil layers.

Time series of soil liquid content (kg/m³) at four observation locations (Asheville, Buncombe; Busick, Yancey; Boone, Watauga; Jefferson, Ashe) showing hourly evolution during extreme precipitation event.

Key Results

Two-way land-atmosphere coupling effectively captures soil moisture-precipitation feedbacks during extreme events.
Runoff generation and river discharge are accurately simulated at high resolution.
Soil water dynamics show realistic response to precipitation forcing with multi-hour memory effects.
The model demonstrates capability to simulate coupled hydro-atmospheric extremes with kilometer-scale detail.

This work extends coupled modeling capabilities to include detailed land surface hydrology, with implications for weather forecasting, hydrological prediction, and climate research.

Reference

Mouallem, J., Malyshev, S., Tan, Z., Shevliakova, E., Gao, K., Harris, L., Benson, R., Cooke, W., Zadeh, N., and Chilutti, L.: Development of a high-resolution coupled SHiELD-MOM6-LM4 – Part 2: Model overview, coupling technique, and evaluation of hydrological extremes during Hurricane Helene, Geoscientific Model Development (accepted), 2026.

SHiELD-MOM6: High-Resolution Coupled Atmosphere-Ocean Modeling

Fri, 26 Sep 2025 00:00:00 +0000

What I developed

The coupling framework connecting SHiELD, MOM6, and SIS2 through FMS
Exchange-grid infrastructure for conservative flux exchange between components
High-resolution coupled atmosphere-ocean-ice model configurations
Evaluation of hurricane-ocean interaction, including Hurricane Helene (2024)

Motivation

Air-sea interactions drive storm intensity and ocean response. This coupled system captures two-way feedback between the atmosphere and ocean at kilometer scales, enabling accurate simulations of hurricane-ocean interactions and coastal impacts.

Overview

We present a new high-resolution coupled atmosphere-ocean model, SHiELD-MOM6, which integrates GFDL’s advanced atmospheric model, the System for High-resolution modeling for Earth-to-Local Domain (SHiELD), the Modular Ocean Model version 6 (MOM6), and the Sea Ice Simulator (SIS2).

The model leverages the Flexible Modeling System (FMS) coupler and its innovative exchange grid to enable a robust and scalable two-way interaction between the atmosphere and ocean. The atmospheric component is built on the non-hydrostatic Finite-Volume Cubed-Sphere Dynamical Core (FV3) with the latest version of the SHiELD physics parametrization suite, while the ocean component is the latest version of MOM, supporting kilometer-scale high-resolution and regional applications.

Coupling infrastructure

The SHiELD-MOM6 model employs the Flexible Modeling System (FMS) coupler, which facilitates the exchange of information between the atmospheric and oceanic components. The exchange grid ensures accurate and efficient communication, enabling the two-way interaction necessary for realistic coupled simulations.

Schematic of a one-dimensional exchange grid and communication map between the atmosphere and ice components at different resolutions. The red sides of the arrow indicate the step where variables are projected from the exchange grid. The light-blue and mauve sides of the arrows represent the projection of variables onto the exchange grid from the atmosphere or ice components, respectively.

Hurricane Helene (2024)

Validation is demonstrated through a suite of experiments, including idealized hurricane simulations and a realistic North Atlantic case study featuring Hurricane Helene 2024. The animation below shows the simulated sea level pressure and 10 m winds (left) alongside the sea surface temperature anomaly and ocean surface currents (right) as the storm crosses the Gulf.

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Hurricane Helene (2024): sea level pressure and surface winds (left); sea surface temperature change and ocean currents (right). The cold wake and upwelling behind the storm are captured by the two-way coupling.

Scalability

Scalability tests have been conducted to evaluate the model’s performance on massively parallel computing systems. The results demonstrate that SHiELD-MOM6 maintains high computational efficiency as the number of processors increases, ensuring that high-resolution coupled simulations can be performed within practical timeframes

Strong scaling (a) and weak scaling (b): actual speedup/efficiency (red circles) compared to ideal speedup/efficiency (black squares) as a function of the number of PEs.

Key results

Air-sea interactions are effectively captured, both in storm intensity and structure and in the ocean response.
The coupling reproduces ocean phenomena such as storm-induced upwelling, the cold wake, and sea level changes.
Scalability tests confirm the model’s computational efficiency on massively parallel systems.

This work establishes a unified, modular cornerstone for advancing high-resolution coupled modeling, with significant implications for weather forecasting and climate research.

Reference

Mouallem, J., Gao, K., Reichl, B. G., Chilutti, L., Harris, L., Benson, R., Zadeh, N., Chen, J., Chen, J.-H., and Zhang, C.: Development of a high-resolution coupled SHiELD-MOM6 model – Part 1: Model overview, coupling technique, and validation in a regional setup, Geoscientific Model Development, 18(18), 6461-6478, 2025. https://doi.org/10.5194/gmd-18-6461-2025

A Minimal, Adiabatic Example of Sudden Stratospheric Warming

Mon, 01 Sep 2025 00:00:00 +0000

Motivation

Sudden stratospheric warmings have profound impacts on surface weather weeks later. This idealized modeling study isolates the key physical mechanisms driving SSW dynamics, building intuition and validating model representations of stratospheric-tropospheric coupling.

Overview

Sudden Stratospheric Warmings (SSW) are extreme events that can significantly impact weather patterns on short, subseasonal and seasonal timescales. In this study we present a new idealized test case of an SSW event implemented in GFDL’s FV3 dynamical core.

Setup

The initial condition features a wintertime stratospheric circulation with a westerly jet in the Northern Hemisphere and an easterly jet in the Southern Hemisphere. In the absence of tropospheric wave forcing, the model preserves this stratospheric circulation for approximately 200 days, which makes it a clean baseline.

To induce an SSW, we introduce a moving mountain that generates planetary waves of a prescribed zonal wavenumber.

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Animation of the moving mountain forcing used to generate planetary waves of a prescribed zonal wavenumber.

The moving mountain is introduced through a time-dependent surface geopotential perturbation,

$$ \phi’ = g h_0 \sin\left(\frac{r,\mathrm{time}}{20}\right) \sin^2\left[ \frac{\pi(\phi-\phi_1)}{\phi_2-\phi_1} \right] \cos\left( z_w\lambda+\frac{10sr,\mathrm{time}}{360} \right), \qquad \phi_2\geq\phi\geq\phi_1. $$

where (g) is gravitational acceleration, ($h_0$) is the mountain height, ($\phi_1$) and ($\phi_2$) define its latitudinal extent, ($z_w$) is the zonal wavenumber, ($s$) controls the phase speed, and ($r$) controls the temporal forcing frequency. The westward-moving mountain generates planetary waves that propagate upward into the stratosphere and interact with the polar vortex.

Results

The Hovmöller diagram shows the temporal evolution of the zonal-wavenumber components of the 10 hPa zonal wind. The growth and propagation of the planetary-wave components illustrate how the imposed forcing develops and interacts with the stratospheric circulation leading up to the SSW.

Hovmoller diagram for decomposed zonal wind amplitudes at 10⁢ℎ⁡𝑃⁢𝑎 for a perturbed simulation, first row shows wavenumber 0, 1, 2, and 3. Time goes upward in days. Second row shows the decomposed wavenumber 1, 2, and 3 components in zonal winds in (m/s)

The animation shows the evolution of the zonal-mean Eliassen–Palm (EP) flux and its divergence. The upward propagation of EP flux demonstrates the transport of planetary-wave activity into the stratosphere, followed by enhanced wave–mean-flow interaction and deceleration of the polar-night jet.

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Zonal-mean Eliassen–Palm (EP) flux vectors (arrows) and EP flux divergence (shading, in m/s/day). Gray contours denote the zonal-mean zonal wind (in m/s), with solid lines for positive values and dashed lines for negative values.

Polar view of the two SSW regimes obtained in the idealized setup: wavenumber-1 forcing produces a vortex displacement event (left), while wavenumber-2 forcing produces a vortex split event (right).

Wavenumber-1 forcing leads to a vortex displacement SSW.
Wavenumber-2 forcing produces a vortex split SSW.

Both are consistent with observations and the published literature.

This minimal setup offers a controlled environment for studying SSW dynamics and serves as a useful testbed for evaluating the ability of dynamical cores to capture key stratospheric processes and troposphere-stratosphere interactions.

Reference

Mouallem, J., Yao, W., Harris, L., Lin, S.-J., and Chen, X.: A Minimal, Adiabatic Example of Sudden Stratospheric Warming, Journal of Advances in Modeling Earth Systems, 17(9), 2025. https://doi.org/10.1029/2024MS004760

Targeted Particle Delivery via Vortex Ring Reconnection

Fri, 01 Oct 2021 00:00:00 +0000

Motivation

Precise particle targeting is important in manufacturing, propulsion, and medical applications. This work shows how vortex ring dynamics can coherently transport particles to specific wall locations, with design parameters (ring size, Stokes number) controlling delivery accuracy.

Concept

A conceptual model for targeted particle delivery is proposed using controlled vortex ring reconnection. Particles entrained in the core of a vortex ring are efficiently transported as the ring advects by self-induction.

Left: initial particle seeding within the cores of the two vortex rings. Right: the reconnection sequence — first reconnection, second reconnection, and pinch off — that redirects the particles toward the sidewalls.

Mechanism

A pair of these particle-transporting vortex rings traveling in the streamwise direction along parallel trajectories will mutually interact, resulting in a pair of vortex reconnection events. The reconnection causes a topological change to the ring, accompanied by a rapid repulsion in the plane perpendicular to the direction of travel. This effectively transports the particles toward the desired location on the sidewalls of a ducted flow.

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Simulation of the two particle-laden vortex rings advecting, interacting, and reconnecting inside the duct.

In addition to proposing this conceptual model, we identify the dominant physics of the process and the design considerations required to achieve targeted delivery.

Particle inertia sets the delivery

Whether the particles actually follow the rings is governed by the Stokes number. Low-inertia particles stay locked to the ring cores and are carried coherently through both reconnections, while high-inertia particles decouple from the vortex and disperse before reaching the wall.

Mean streamwise particle position (left) and mean wall-normal particle position (right) for St = 0.1, 1 and 10. Shaded bands show one standard deviation and the dashed lines mark the two reconnection events. At St = 0.1 and St = 1 the particles track the rings and are delivered together; at St = 10 they lag and spread widely.

Design considerations

The ring radius, relative to the channel width, controls how strongly the rings repel after reconnection and therefore where on the sidewall the particles arrive. This makes ring size the primary design parameter for aiming the delivery.

Spreading angle θ after reconnection for three ring sizes, with R set by the channel width W: R = 0.15W (blue), R = 0.125W (green) and R = 0.1W (red). Larger rings separate more aggressively, moving the impact point further upstream.

Reference

Mouallem, J., Daryan, H., Wawryk, J., Pan, Z., and Hickey, J.-P.: Targeted particle delivery via vortex ring reconnection, Physics of Fluids, 33(10), 2021. https://doi.org/10.1063/5.0066443

Induction Heating of Dispersed Metallic Particles in a Turbulent Flow

Sun, 01 Nov 2020 00:00:00 +0000

Motivation

Induction heating of particles in flight is relevant to advanced combustion and energy conversion systems. This DNS study reveals how rapid heating reduces particle clustering and alters turbulent structures, informing the design of more efficient heating systems.

Overview

Inductively heated solid particles dispersed within a decaying isotropic turbulent carrier gas are investigated via Direct Numerical Simulation (DNS). The multiphase simulations account for the compressibility and temperature-dependent viscosity of the carrier gas.

We develop a semi-empirical model for solid particle heating through hysteresis and Joule mechanisms, as these dispersed particles are heated by an external high-frequency alternating magnetic field.

Validation of the semi-empirical induction heating model against the experimental data of Bae et al. (2015). Symbols are measurements for four particle loadings (5 to 20 phr); solid lines are the model, each with its own induction heating timescale. Higher loading heats faster and reaches a higher equilibrium temperature.

Gas temperature field (colors) and particle positions (black dots) in a 2D slice of the domain at t = 10, for increasing particle thermal response time (left to right). Hotter gas develops around the particle-laden regions as the thermal fluctuations grow.

Key results

The growth of the Kolmogorov length scale is due to a simultaneous increase in viscosity and decrease in the dissipation rate.
The temperature-dependent viscosity of the gas leads to a faster decay of the gas turbulent kinetic energy, mainly through a loss of energy at intermediate wavenumbers.
The gas and particle thermal fluctuations are inversely correlated, set by the relative thermodynamic timescales.
Two regimes appear in the temperature spectrum: while thermal fluctuations grow, thermal energy increases monotonically in the low-wavenumber range; once they decay, the decay occurs across the entire spectrum.
Aggressive heating (shorter induction heating timescales) reduces particle clustering, whereas the particle thermal response time shows no such effect.

Heating de-clusters the particles

Preferential concentration is measured with the radial distribution function. The unheated case shows the strongest clustering at small separations, and the clustering weakens monotonically as the induction heating becomes more aggressive, while changing the particle thermal response time leaves the distribution essentially unchanged.

Radial distribution function of the particles at t = 30 for all cases, with a zoom on the small-separation limit. The unheated reference (I∞T0) clusters the most; shorter induction heating timescales (I10T10 to I01T10) progressively reduce clustering, while varying the thermal response time (I1T10, I1T100, I1T1000) has little effect.

Reference

Mouallem, J. and Hickey, J.-P.: Induction heating of dispersed metallic particles in a turbulent flow, International Journal of Multiphase Flow, 132, 103414, 2020. https://doi.org/10.1016/j.ijmultiphaseflow.2020.103414

Macro-Scale Effects on Sub-Grid Closures in Gas-Solid Riser Flows

Fri, 01 Jun 2018 00:00:00 +0000

Motivation

Sub-grid closures for two-fluid models are traditionally derived at a single scale, but this work demonstrates that flow topology at the system scale strongly affects closure accuracy. Accounting for these effects is essential for predictive industrial riser flow simulations.

Background

Filtered two-fluid formulations of gas-solid fluidized flows require closure models to deal with sub-grid filtered parameters. These closures are derived by filtering the results of meso-scale highly resolved simulations (HRS) with two-fluid modeling, and then applying them on the coarse large-scale simulation (LSS) grid.

Closure strategy: a highly resolved simulation with the two-fluid model and microscopic closures is filtered to provide sub-grid closures for the coarse, large-scale filtered two-fluid model.

The question

Trusting in scale separation, the correlation of filtered parameters has traditionally been performed against meso-scale filtered data only, disregarding any macro-scale effects. In this work, the correctness of that practice is tested — and it fails.

Approach

Two macro-scale parameters associated with flow topology are considered for their effects on the relevant filtered parameters: the average solid volume fraction and the average gas Reynolds number. Highly resolved simulations are filtered while holding each of these macro-scale parameters constant at various levels. The interest is directed toward the dilute conditions typical of riser flows.

Instantaneous solid volume fraction for increasing solids loading (left to right) and increasing gas Reynolds number (top to bottom). The cluster structure — and therefore the sub-grid closure — depends strongly on both macro-scale parameters.

The drag closure is not scale separated

The drag coefficient correction H, the single most influential sub-grid term, is the clearest evidence of the failure of scale separation. Correlating H against the meso-scale filtered variables alone leaves a systematic spread that is set entirely by the macro-scale state of the flow.

Drag coefficient correction H against the filtered solid volume fraction. (a) Effect of the domain average gas Reynolds number at fixed solids loading; (b) effect of the domain average solid volume fraction at fixed Reynolds number. Curves that should collapse if scale separation held instead fan out by a factor of two or more.

The same holds for the stress closures

The effect is not limited to drag. The filtered solid pressure, which closes the solid-phase momentum equation, shifts by roughly an order of magnitude across the range of macro-scale conditions at an otherwise identical filtered state.

Dimensionless filtered solid pressure against the filtered solid volume fraction. (a) Varying the domain average gas Reynolds number; (b) varying the domain average solid volume fraction. The vertical spread at fixed filtered state is the macro-scale signature that traditional closures ignore.

Conclusion

Results show that both macro-scale parameters should be accounted for in sub-grid correlations if higher accuracy is to be achieved.

Reference

Mouallem, J., Chavez-Cussy, N., Niaki, S. R. A., Milioli, C. C., and Milioli, F. E.: On the effects of the flow macro-scale over meso-scale filtered parameters in gas-solid riser flows, Chemical Engineering Science, 182, 200-211, 2018. https://doi.org/10.1016/j.ces.2018.02.039

Development of a high-resolution coupled SHiELD-MOM6-LM4 – Part 2: Model overview, coupling technique, and evaluation of hydrological extremes during Hurricane Helene

Thu, 27 Aug 2026 00:00:00 +0000

Integrating a Three-Dimensional TKE-Based Subgrid Diffusion Scheme Into GFDL FV3

Mon, 01 Jun 2026 00:00:00 +0000

Development of a high-resolution coupled SHiELD-MOM6 model – Part 1: Model overview, coupling technique, and validation in a regional setup

Fri, 26 Sep 2025 00:00:00 +0000

A Minimal, Adiabatic Example of Sudden Stratospheric Warming

Mon, 01 Sep 2025 00:00:00 +0000

Impact of petrophysical properties on CO2 residual trapping in limestone formations

Mon, 01 Sep 2025 00:00:00 +0000

Analysis of finite-volume transport schemes on cubed-sphere grids and an accurate scheme for divergent winds

Sat, 01 Feb 2025 00:00:00 +0000

What Are the Finger-Like Clouds in the Hurricane Inner-Core Region?

Mon, 16 Dec 2024 00:00:00 +0000

Bridging the Gap Between Global Weather Prediction and Global Storm-Resolving Simulation: Introducing the GFDL 6.5-km SHiELD

Sun, 01 Dec 2024 00:00:00 +0000

Implementation of the Novel Duo-Grid in GFDL's FV3 Dynamical Core

Fri, 01 Dec 2023 00:00:00 +0000

On the effects of the flow macro-scale over sub-grid modelling in dense gas–solid fluidized flows

Mon, 28 Nov 2022 00:00:00 +0000

Multiple same-level and telescoping nesting in GFDL's dynamical core

Tue, 07 Jun 2022 00:00:00 +0000

Targeted particle delivery via vortex ring reconnection

Fri, 01 Oct 2021 00:00:00 +0000

Improving the accuracy of two-fluid sub-grid modeling of dense gas-solid fluidized flows

Fri, 01 Jan 2021 00:00:00 +0000

Induction heating of dispersed metallic particles in a turbulent flow

Sun, 01 Nov 2020 00:00:00 +0000

Experimental investigation of effects of magnetic field on performance, combustion, and emission characteristics of a spark ignition engine

Sun, 01 Mar 2020 00:00:00 +0000

Targeted turbulent structure control in wall-bounded flows via localized heating

Sun, 01 Mar 2020 00:00:00 +0000

Some accuracy related aspects in two-fluid hydrodynamic sub-grid modeling of gas-solid riser flows

Wed, 01 Jan 2020 00:00:00 +0000

Picard–Newton iterative algorithm to solve the potential flow equation for different turbomachinery flow regimes

Thu, 01 Aug 2019 00:00:00 +0000

Macro-scale effects over filtered and residual stresses in gas-solid riser flows

Sat, 23 Feb 2019 00:00:00 +0000

Experimental and simulation investigation of effect of biodiesel-diesel blend on performance, combustion and emission characteristics of a diesel engine

Sun, 01 Jul 2018 00:00:00 +0000

On the effects of the flow macro-scale over meso-scale filtered parameters in gas-solid riser flows

Fri, 01 Jun 2018 00:00:00 +0000

Mon, 01 Jan 0001 00:00:00 +0000

Joseph Mouallem

The Duo-Grid and Cubed-Sphere Grid Imprinting

Motivation

The problem: grid imprinting

The Duo-Grid

Validation

Key results

Reference

Multiple Same-Level and Telescoping Grid Nesting

Motivation

Overview

Progressive refinement

Computational design

Availability

Reference

SHiELD-LM4: Coupled Land-Atmosphere Modeling

What I developed

Motivation

Overview

Coupling Infrastructure

Hurricane Helene (2024): Precipitation and Runoff

Soil Moisture and Land Surface Response

Soil Column Interactions

Key Results

Reference

SHiELD-MOM6: High-Resolution Coupled Atmosphere-Ocean Modeling

What I developed

Motivation

Overview

Coupling infrastructure

Hurricane Helene (2024)

Scalability

Key results

Reference

A Minimal, Adiabatic Example of Sudden Stratospheric Warming

Motivation

Overview

Setup

Results

Reference

Targeted Particle Delivery via Vortex Ring Reconnection

Motivation

Concept

Mechanism

Particle inertia sets the delivery

Design considerations

Reference

Induction Heating of Dispersed Metallic Particles in a Turbulent Flow

Motivation

Overview

Key results

Heating de-clusters the particles

Reference

Macro-Scale Effects on Sub-Grid Closures in Gas-Solid Riser Flows

Motivation

Background

The question

Approach

The drag closure is not scale separated

The same holds for the stress closures

Conclusion

Reference

Development of a high-resolution coupled SHiELD-MOM6-LM4 – Part 2: Model overview, coupling technique, and evaluation of hydrological extremes during Hurricane Helene

Integrating a Three-Dimensional TKE-Based Subgrid Diffusion Scheme Into GFDL FV3

Development of a high-resolution coupled SHiELD-MOM6 model – Part 1: Model overview, coupling technique, and validation in a regional setup

A Minimal, Adiabatic Example of Sudden Stratospheric Warming

Impact of petrophysical properties on CO2 residual trapping in limestone formations

Analysis of finite-volume transport schemes on cubed-sphere grids and an accurate scheme for divergent winds

What Are the Finger-Like Clouds in the Hurricane Inner-Core Region?

Bridging the Gap Between Global Weather Prediction and Global Storm-Resolving Simulation: Introducing the GFDL 6.5-km SHiELD

Implementation of the Novel Duo-Grid in GFDL's FV3 Dynamical Core

On the effects of the flow macro-scale over sub-grid modelling in dense gas–solid fluidized flows

Multiple same-level and telescoping nesting in GFDL's dynamical core

Targeted particle delivery via vortex ring reconnection

Improving the accuracy of two-fluid sub-grid modeling of dense gas-solid fluidized flows

Induction heating of dispersed metallic particles in a turbulent flow

Experimental investigation of effects of magnetic field on performance, combustion, and emission characteristics of a spark ignition engine

Targeted turbulent structure control in wall-bounded flows via localized heating

Some accuracy related aspects in two-fluid hydrodynamic sub-grid modeling of gas-solid riser flows

Picard–Newton iterative algorithm to solve the potential flow equation for different turbomachinery flow regimes