arXiv subjects

Jonas Latt

Publications and source records attributed to Jonas Latt.

21 records · Page 2Linked to original sources

arXiv2015

A physical description of the adhesion and aggregation of platelets

The early stages of clot formation in blood vessels involve platelets adhesion-aggregation. Although these mechanisms have been extensively studied, gaps in their understanding still persist. We have performed detailed in-vitro experiments and developed a numerical model to better describe and understand this phenomenon. Unlike previous studies, we took into account both activated and non-activated platelets, as well as the 3D nature of the aggregation process. Our investigation reveals that blood albumin is a major parameter limiting platelet adhesion and aggregation. Our results also show that the well accepted Zydney-Colton shear-induced diffusivity is much too low to explain the observed deposition rate. Simulations are in very good agreement with observations and provide quantitative estimates of the adhesion and aggregation rates that are hard to measure experimentally.

physics.bio-ph↗

arXiv2005

Spatial Coupling of a Lattice Boltzmann fluid model with a Finite Difference Navier-Stokes solver

In multiscale, multi-physics applications, there is an increasing need for coupling numerical solvers that are each applied to a different part of the problem. Here we consider the case of coupling a Lattice Boltzmann fluid model and a Finite Difference Navier-Stokes solver. The coupling is implemented so that the entire computational domain can be divided in two regions, with the FD solver running on one of them and the LB one on the other. We show how the various physical quantities of the two approaches should be related to ensure a smooth transition at the interface between the regions. We demonstrate the feasibility of the method on the Poiseuille flow, where the LB and FD schemes are used on adjacent sub-domains. The same idea can be also developed to couple LB models with Finite Volumes, or Finite Elements calculations. The motivation for developing such a type of coupling is that, depending on the geometry of the flow, one technique can be more efficient, less memory consuming, or physically more appropriate than the other in some regions (e.g. near the boundaries), whereas the converse is true for other parts of the same system. We can also imagine that a given system solved, say by FD, can be augmented in some spatial regions with a new physical process that is better treated by a LB model. Our approach allows us to only modify the concerned region without altering the rest of the computation.

physics.comp-ph↗

arXiv2005

Lattice Boltzmann Method with regularized non-equilibrium distribution functions

A new lattice Boltzmann (LB) model is introduced, based on a regularization of the pre-collision distribution functions in terms of the local density, velocity, and momentum flux tensor. The model dramatically improves the precision and numerical stability for the simulation of fluid flows by LB methods. This claim is supported by simulation results of some 2D and 3D flows.

physics.flu-dyn↗