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The accuracy and computational cost of a large eddy simulation are highly dependent on the computational grid. Building optimal grids manually from a priori knowledge is not feasible in most practical use cases; instead, solution-adaptive…

Fluid Dynamics · Physics 2023-01-31 Marcel Blind , Ali Berk Kahraman , Johan Larsson , Andrea Beck

Wall-models are essential for enabling large-eddy simulations (LESs) of realistic problems at high Reynolds numbers. The present study is focused on approaches that directly model the wall shear stress, specifically on filling the gap…

Fluid Dynamics · Physics 2015-12-01 Stefan Hickel , Emile Touber , Julien Bodart , Johan Larsson

When approximating the expectations of a functional of a solution to a stochastic differential equation, the numerical performance of deterministic quadrature methods, such as sparse grid quadrature and quasi-Monte Carlo (QMC) methods, may…

Computational Finance · Quantitative Finance 2022-11-24 Christian Bayer , Chiheb Ben Hammouda , Raúl Tempone

A heuristic formula for 5-point approximation of the first derivative of an unknown function whose values are measured with an error at unequally spaced points is proposed. The derivative at a given point is calculated using the effective…

Data Analysis, Statistics and Probability · Physics 2022-09-14 Emmanuil Beygelzimer , Yan Beygelzimer

We present an adaptive finite element method for the incompressible Navier--Stokes equations based on a standard splitting scheme (the incremental pressure correction scheme). The presented method combines the efficiency and simplicity of a…

Numerical Analysis · Mathematics 2012-05-15 Kristoffer Selim , Anders Logg , Mats G. Larson

Summation-by-parts (SBP) finite difference methods have several desirable properties for second-order wave equations. They combine the computational efficiency of narrow-stencil finite difference operators with provable stability on…

Numerical Analysis · Mathematics 2020-09-29 Martin Almquist , Eric M. Dunham

For elliptic interface problems in two- and three-dimensions with a possible very low regularity, this paper establishes a priori error estimates for the Raviart-Thomas and Brezzi-Douglas-Marini mixed finite element approximations. These…

Numerical Analysis · Mathematics 2019-03-01 Shun Zhang

Wall-based spanwise forcing has been experimentally used with success by Auteri et al. (Phys. Fluids vol. 22, 2010, 115103) to obtain large reductions of turbulent skin-friction drag and considerable energy savings in a pipe flow. The…

Fluid Dynamics · Physics 2024-01-23 Emanuele Gallorini , Maurizio Quadrio

We consider numerical simulation of the isotropic elastic wave equations arising from seismic applications with non-trivial land topography. The more flexible finite element method is applied to the shallow region of the simulation domain…

Numerical Analysis · Mathematics 2018-12-26 Longfei Gao , David Keyes

We design a primal-dual stabilized finite element method for the numerical approximation of a data assimilation problem subject to the acoustic wave equation. For the forward problem, piecewise affine, continuous, finite element functions…

Numerical Analysis · Mathematics 2023-05-10 Erik Burman , Ali Feizmohammadi , Lauri Oksanen

We introduce a wall model (WM) for large-eddy simulation (LES) applicable to rough surfaces with Gaussian and non-Gaussian distributions for both transitionally and fully rough regimes. The model is applicable to arbitrary complex…

Fluid Dynamics · Physics 2025-03-19 Rong Ma , Adrian Lozano-Duran

We propose a numerical strategy to generate the anisotropic meshes and select the appropriate stabilized parameters simultaneously for two dimensional convection-dominated convection-diffusion equations by stabilized continuous linear…

Numerical Analysis · Mathematics 2016-02-09 Yana Di , Hehu Xie , Xiaobo Yin

Predictions of the spatial representation of instantaneous wall-bounded flows, via coherent structure-based models, are highly sensitive to the geometry of the representative structures employed by them. In this study, we propose a…

Fluid Dynamics · Physics 2024-04-30 Rahul Deshpande , Charitha M. de Silva , Myoungkyu Lee , Jason P. Monty , Ivan Marusic

Wall-bounded turbulent shear flows are known to exhibit universal small-scale dynamics that are modulated by large-scale flow structures. Strong pressure gradients complicate this characterization, however; they can cause significant…

Fluid Dynamics · Physics 2023-09-18 Sean P. Carney , Robert D. Moser

Friction drag from a turbulent fluid moving past or inside an object plays a crucial role in domains as diverse as transportation, public utility infrastructure, energy technology, and human health. As a direct measure of the shear-induced…

Fluid Dynamics · Physics 2023-10-19 Esther Lagemann , Steven L. Brunton , Christian Lagemann

In order to accelerate implementation of hyperelastic materials for finite element analysis, we developed an automatic numerical algorithm that only requires the strain energy function. This saves the effort on analytical derivation and…

Computational Engineering, Finance, and Science · Computer Science 2016-09-20 Yuxiang Wang , Gregory J. Gerling

A modified-Bloch equation based on the fractal derivative is proposed to analyze pulsed field gradient (PFG) anomalous diffusion. Anomalous diffusion exists in many systems such as in polymer or biological systems. PFG anomalous diffusion…

Chemical Physics · Physics 2017-09-19 Guoxing Lin

Normalising-flow variational inference (VI) can approximate complex posteriors, yet single-flow models often behave inconsistently across qualitatively different distributions. We propose Adaptive Mixture Flow Variational Inference…

Machine Learning · Computer Science 2025-10-03 Benjamin Wiriyapong , Oktay Karakuş , Kirill Sidorov

Recent work shows that path gradient estimators for normalizing flows have lower variance compared to standard estimators for variational inference, resulting in improved training. However, they are often prohibitively more expensive from a…

Machine Learning · Computer Science 2024-03-26 Lorenz Vaitl , Ludwig Winkler , Lorenz Richter , Pan Kessel

We introduce Soft Anisotropic Diagrams (SAD), an explicit and differentiable image representation parameterized by a set of adaptive sites in the image plane. In SAD, each site specifies an anisotropic metric and an additively weighted…

Computer Vision and Pattern Recognition · Computer Science 2026-04-28 Laki Iinbor , Zhiyang Dou , Wojciech Matusik