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A novel reduced order model (ROM) for incompressible flows is developed by performing a Galerkin projection based on a fully (space and time) discrete full order model (FOM) formulation. This 'discretize-then-project' approach requires no…

We investigate a novel monolithic algebraic multigrid (AMG) preconditioner for the Taylor-Hood ($\pmb{\mathbb{P}}_2/\mathbb{P}_1$) and Scott-Vogelius ($\pmb{\mathbb{P}}_2/\mathbb{P}_1^{disc}$) discretizations of the Stokes equations. The…

Numerical Analysis · Mathematics 2024-09-04 Alexey Voronin , Scott MacLachlan , Luke N. Olson , Raymond Tuminaro

We assess the suitability of Reynolds-Averaged Navier-Stokes (RANS) simulation using the Spallart-Almaras (SA) turbulence model as a closure in analysing the performance of fluidic Active Flow Control (AFC) applications. In particular, we…

Fluid Dynamics · Physics 2024-07-31 Navid Monshi Tousi , Josep M. Bergada , Fernando Mellibovsky

This paper considers approximate smoothing for discretely observed non-linear stochastic differential equations. The problem is tackled by developing methods for linearising stochastic differential equations with respect to an arbitrary…

Methodology · Statistics 2019-01-21 Filip Tronarp , Simo Särkkä

Topology optimization problems generally support multiple local minima, and real-world applications are typically three-dimensional. In previous work [I. P. A. Papadopoulos, P. E. Farrell, and T. M. Surowiec, Computing multiple solutions of…

Numerical Analysis · Mathematics 2022-11-23 Ioannis P. A. Papadopoulos , Patrick E. Farrell

The focus of this work is on the construction and analysis of optimal-order multigrid preconditioners to be used in the Newton-Krylov method for a distributed optimal control problem constrained by the stationary Navier-Stokes equations. As…

Numerical Analysis · Mathematics 2018-11-22 Ana Maria Soane , Andrei Draganescu

Systems driven by multiple physical processes are central to many areas of science and engineering. Time discretization of multiphysics systems is challenging, since different processes have different levels of stiffness and characteristic…

Numerical Analysis · Mathematics 2022-01-19 Adrian Sandu , Michael Günther , Steven Roberts

We present two different reduced order strategies for incompressible parameterized Navier-Stokes equations characterized by varying Reynolds numbers. The first strategy deals with low Reynolds number (laminar flow) and is based on a…

Numerical Analysis · Mathematics 2023-08-08 Saddam Hijazi , Shafqat Ali , Giovanni Stabile , Francesco Ballarin , Gianluigi Rozza

Solving the Reynolds-averaged Navier-Stokes equations (RANS) closed with an eddy viscosity computed through a turbulence model is still the leading approach for Computational Fluid Dynamics simulations. Unfortunately, universal models with…

Fluid Dynamics · Physics 2025-09-18 Marco Castelletti , Maurizio Quadrio

The solution of saddle-point problems, such as the Stokes equations, is a challenging task, especially in large-scale problems. Multigrid methods are one of the most efficient solvers for such systems of equations and can achieve…

Numerical Analysis · Mathematics 2022-04-13 S. Saberi , G. Meschke , A. Vogel

We consider iterative methods for solving the linearised Navier-Stokes equations arising from two-phase flow problems and the efficient preconditioning of such systems when using mixed finite element methods. Our target application is…

Numerical Analysis · Mathematics 2020-05-18 Niall Bootland , Alistair Bentley , Christopher Kees , Andrew Wathen

Advanced Krylov subspace methods are investigated for the solution of large sparse linear systems arising from stiff adjoint-based aerodynamic shape optimization problems. A special attention is paid to the flexible inner-outer GMRES…

Numerical Analysis · Mathematics 2024-04-30 Mehdi Jadoui , Christophe Blondeau , Emeric Martin , Florent Renac , François-Xavier Roux

A local artificial neural network (LANN) framework is developed for turbulence modeling. The Reynolds-averaged Navier-Stokes (RANS) unclosed terms are reconstructed by artificial neural network (ANN) based on the local coordinate system…

Fluid Dynamics · Physics 2021-09-08 Chenyue Xie , Xiangming Xiong , Jianchun Wang

This study presents a novel approach for enhancing Reynolds-averaged Navier-Stokes (RANS) turbulence modeling through the application of a Relative Importance Term Analysis (RITA) methodology to develop a new zonally-augmented $k-\omega$…

Fluid Dynamics · Physics 2025-11-26 Tyler Buchanan , Monica Lăcătuş , Alastair West , Richard P. Dwight

A Finite-Volume based POD-Galerkin reduced order modeling strategy for steady-state Reynolds averaged Navier--Stokes (RANS) simulation is extended for low-Prandtl number flow. The reduced order model is based on a full order model for which…

Fluid Dynamics · Physics 2020-08-04 Kelbij Star , Giovanni Stabile , Gianluigi Rozza , Joris Degroote

Cloud and precipitation microphysics packages in atmospheric general circulation models typically use first-order time integration methods with a large time step, requiring ad hoc limiters and substepping of the sedimentation scheme to…

Atmospheric and Oceanic Physics · Physics 2026-03-13 Justin Dong , Sean P. Santos , Steven B. Roberts , Christopher J. Vogl , Carol S. Woodward

This article provides a reduced-order modelling framework for turbulent compressible flows discretized by the use of finite volume approaches. The basic idea behind this work is the construction of a reduced-order model capable of providing…

Fluid Dynamics · Physics 2024-05-31 Matteo Zancanaro , Valentin Nkana Ngan , Giovanni Stabile , Gianluigi Rozza

Multiphase flows are an important class of fluid flow and their study facilitates the development of diverse applications in industrial, natural, and biomedical systems. We consider a model that uses a continuum description of both phases…

Fluid Dynamics · Physics 2025-08-04 Bindi M. Nagda , Aaron Barrett , Boyce E. Griffith , Aaron L. Fogelson , Jian Du

Layer-wise preconditioning methods are a family of memory-efficient optimization algorithms that introduce preconditioners per axis of each layer's weight tensors. These methods have seen a recent resurgence, demonstrating impressive…

Machine Learning · Computer Science 2025-02-05 Thomas T. Zhang , Behrad Moniri , Ansh Nagwekar , Faraz Rahman , Anton Xue , Hamed Hassani , Nikolai Matni

Reynolds-averaged Navier-Stokes (RANS) equations are widely used in engineering turbulent flow simulations. However, RANS predictions may have large discrepancies due to the uncertainties in modeled Reynolds stresses. Recently, Wang et al.…

Fluid Dynamics · Physics 2018-09-11 Jin-Long Wu , Heng Xiao , Eric Paterson