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A novel smooth immersed boundary method (IBM) based on a direct-forcing formulation is proposed to simulate incompressible dense particle-laden flows. This IBM relies on a regularization of the transfer function between the Eulerian grid…

Computational Physics · Physics 2023-04-24 Victor Chéron , Fabien Evrard , Berend van Wachem

We present a non-nested multilevel algorithm for solving the Poisson equation discretized at scattered points using polyharmonic radial basis function (PHS-RBF) interpolations. We append polynomials to the radial basis functions to achieve…

Numerical Analysis · Mathematics 2021-04-29 Anand Radhakrishnan , Michael Xu , Shantanu Shahane , Surya Pratap Vanka

The Immersed Boundary method is a simple, efficient, and robust numerical scheme for solving PDE in general domains, yet for fluid problems it only achieves first-order spatial accuracy near embedded boundaries for the velocity field and…

Numerical Analysis · Mathematics 2017-03-08 David B. Stein , Robert D. Guy , Becca Thomases

We develop an encounter-based approach for describing restricted diffusion with a gradient drift towards a partially reactive boundary. For this purpose, we introduce an extension of the Dirichlet-to-Neumann operator and use its eigenbasis…

Chemical Physics · Physics 2022-10-10 Denis S. Grebenkov

A hydrogeological model for the spread of pollution in an aquifer is considered. The model consists in a convection-diffusion-reaction equation involving the dispersion tensor which depends nonlinearly of the fluid velocity. We introduce an…

Numerical Analysis · Mathematics 2020-06-05 Éloïse Comte

This paper uses the generator approach of Stein's method to analyze the gap between steady-state distributions of Markov chains and diffusion processes. Until now, the standard way to invoke Stein's method for this problem was to use the…

Probability · Mathematics 2022-02-15 Anton Braverman

We consider a bulk-membrane-coupled partial differential equation in which a single diffusion equation posed within the unit ball is coupled to a two-component reaction diffusion equation posed on the bounding unit sphere through a linear…

Pattern Formation and Solitons · Physics 2019-10-21 Daniel Gomez

We present a meshfree generalized finite difference method for solving Poisson's equation with a diffusion coefficient that contains jump discontinuities up to several orders of magnitude. To discretize the diffusion operator, we formulate…

Numerical Analysis · Mathematics 2022-09-23 Heinrich Kraus , Jörg Kuhnert , Andreas Meister , Pratik Suchde

We present a novel numerical method for solving the anisotropic diffusion equation in magnetic fields confined to a periodic box which is accurate and provably stable. We derive energy estimates of the solution of the continuous initial…

Numerical Analysis · Mathematics 2025-02-13 Dean Muir , Kenneth Duru , Matthew Hole , Stuart Hudson

A systematic study is carried out on a fully resolved fluid-particle model which couples the Lattice Boltzmann Method (LBM) and the Discrete Element Method (DEM) using an immersed moving boundary technique. Similar algorithms have been…

Computational Physics · Physics 2019-06-21 G. C. Yang , L. Jing , C. Y. Kwok , Y. D. Sobral

Mathematical models describing the spatial spreading and invasion of populations of biological cells are often developed in a continuum modelling framework using reaction-diffusion equations. While continuum models based on linear diffusion…

Cellular Automata and Lattice Gases · Physics 2024-01-23 Matthew J Simpson , Keeley M Murphy , Scott W McCue , Pascal R Buenzli

We consider the mixed Steklov-Neumann spectral problem for the modified Helmholtz equation in a bounded domain when the Steklov condition is imposed on a connected subset of the smooth boundary. In order to deduce the asymptotic behavior in…

Computational Physics · Physics 2025-07-22 Denis S. Grebenkov

This paper develops an approach for solving perpetual discounted optimal stopping problems for multidimensional diffusions, with special emphasis on the $d$-dimensional Wiener process. We first obtain some verification theorems for…

Probability · Mathematics 2016-11-04 Sören Christensen , Fabián Crocce , Ernesto Mordecki , Paavo Salminen

The Immersed Boundary Method (IBM) is a popular numerical approach to impose boundary conditions without relying on body-fitted grids, thus reducing the costly effort of mesh generation. To obtain enhanced accuracy, IBM can be combined with…

Numerical Analysis · Mathematics 2024-01-10 Victor J. Llorente , Jiaqing Kou , Eusebio Valero , Esteban Ferrer

Chemical reactions inside cells are generally considered to happen within fixed-size compartments. Needless to say, cells and their compartments are highly dynamic. Thus, such stringent assumptions may not reflect biochemical reality, and…

Quantitative Methods · Quantitative Biology 2016-02-17 Atiyo Ghosh , Tatiana T. Marquez-Lago

This paper presents a general and robust method for the fluid-structure interaction of membranes and shells undergoing large displacement and large added-mass effects by coupling an immersed-boundary method with a shell finite-element…

Fluid Dynamics · Physics 2023-08-15 Marin Lauber , Gabriel D. Weymouth , Georges Limbert

The Poisson-Boltzmann equation (PBE) is a nonlinear elliptic PDE that arises in biomolecular modeling and is a fundamental tool for structural biology. It is used to calculate electrostatic potentials around an ensemble of fixed charges…

Numerical Analysis · Mathematics 2017-10-12 Cleophas Kweyu , Lihong Feng , Matthias Stein , Peter Benner

We study reaction-diffusion particle systems with several interaction mechanisms. As the number of particles tends to infinity, the system admits a mean-field limit describing the bulk behaviour. We focus on determining the propagation…

Probability · Mathematics 2026-04-21 Matthieu Jonckheere , Seva Shneer

The exact solution of a diffusion$-$reaction model for the trapping and annihilation of positrons in small extended spherical defects (clusters, voids, small precipitates) with competitive rate-limited trapping in vacancy-type point defects…

Materials Science · Physics 2019-04-24 Roland Würschum , Laura Resch , Gregor Klinser

We consider one-dimensional diffusions, with polynomial drift and diffusion coefficients, so that in particular the motion can be space-inhomogeneous, interacting via one-sided reflections. The prototypical example is the well-known model…

Probability · Mathematics 2023-07-05 Theodoros Assiotis