80 citations · 174 across the 12 of their papers we have counts for
13 papers
Effects of resolution inhomogeneity in large-eddy simulation
Gopal R. Yalla, Todd A. Oliver, Sigfried W. Haering +2
Large Eddy Simulation (LES) of turbulence in complex geometries is often conducted using strongly inhomogeneous resolution. The issues associated with resolution inhomogeneity are…
Near wall patch representation of wall bounded turbulence
Sean P. Carney, Björn Engquist, Robert D. Moser
Recent experimental and computational studies indicate that near wall turbulent flows can be characterized by universal small scale autonomous dynamics that are modulated by large…
Multiscale Modeling, Homogenization and Nonlocal Effects: Mathematical and Computational Issues
Qiang Du, Bjorn Engquist, Xiaochuan Tian
In this work, we review the connection between the subjects of homogenization and nonlocal modeling and discuss the relevant computational issues. By further exploring this connect…
Fast algorithm for computing nonlocal operators with finite interaction distance
Xiaochuan Tian, Bjorn Engquist
Developments of nonlocal operators for modeling processes that traditionally have been described by local differential operators have been increasingly active during the last few y…
Seafloor identification in sonar imagery via simulations of Helmholtz equations and discrete optimization
Bjorn Engquist, Christina Frederick, Quyen Huynh +1
We present a multiscale approach for identifying features in ocean beds by solving inverse problems in high frequency seafloor acoustics. The setting is based on Sound Navigation A…
Multiscale numerical methods for passive advection-diffusion in incompressible turbulent flow fields
Yoonsang Lee, Bjorn Engquist
We propose a seamless multiscale method which approximates the macroscopic behavior of the passive advection-diffusion equations with steady incompressible velocity fields with mul…
A mathematical and Physical Model Improves Accuracy in Simulating Solid Material Relaxation Modulus and Viscoelastic Responses
Qinwu Xu, Bjorn Engquist
We propose a new material viscoelastic model and mathematical solution to simulate relaxation modulus and viscoelastic response. The model formula of relaxation modulus is extended…
A parallel directional Fast Multipole Method
Austin R. Benson, Jack Poulson, Kenneth Tran +2
This paper introduces a parallel directional fast multipole method (FMM) for solving N-body problems with highly oscillatory kernels, with a focus on the Helmholtz kernel in three…
Nonuniform sampling and multiscale computation
Björn Engquist, Christina Frederick
In homogenization theory and multiscale modeling, typical functions satisfy the scaling law , where is periodic in the second variable and is the smalles…
A parallel sweeping preconditioner for heterogeneous 3D Helmholtz equations
Jack Poulson, Björn Engquist, Siwei Li +1
A parallelization of a sweeping preconditioner for 3D Helmholtz equations without large cavities is introduced and benchmarked for several challenging velocity models. The setup an…
Sweeping Preconditioner for the Helmholtz Equation: Moving Perfectly Matched Layers
Björn Engquist, Lexing Ying
This paper introduces a new sweeping preconditioner for the iterative solution of the variable coefficient Helmholtz equation in two and three dimensions. The algorithms follow the…
Sweeping Preconditioner for the Helmholtz Equation: Hierarchical Matrix Representation
Björn Engquist, Lexing Ying
The paper introduces the sweeping preconditioner, which is highly efficient for iterative solutions of the variable coefficient Helmholtz equation including very high frequency pro…
Fast Directional Computation for the High Frequency Helmholtz Kernel in Two Dimensions
Björn Engquist, Lexing Ying
This paper introduces a directional multiscale algorithm for the two dimensional -body problem of the Helmholtz kernel with applications to high frequency scattering. The algori…