A Fourier-based methodology without numerical diffusion for conducting dye simulations and particle residence time calculations

TL;DR

This paper presents a Fourier continuation pseudo-spectral method for dye and particle residence time simulations in fluid flows, eliminating numerical diffusion and applicable to both computational and experimental velocity data.

Contribution

It introduces a novel Fourier-based approach that avoids numerical diffusion in dye and particle residence time simulations, with comprehensive convergence and error analysis.

Findings

Successfully applied to 2D cavity flow, aortic dissection, and blood flow in grafts.

Achieves high accuracy without numerical diffusion errors.

Applicable to both simulated and experimental velocity data.

Abstract

Dye experimentation is a widely used method in experimental fluid mechanics for flow analysis or for the study of the transport of particles within a fluid. This technique is particularly useful in biomedical diagnostic applications ranging from hemodynamic analysis of cardiovascular systems to ocular circulation. However, simulating dyes governed by convection-diffusion partial differential equations (PDEs) can also be a useful post-processing analysis approach for computational fluid dynamics (CFD) applications. Such simulations can be used to identify the relative significance of different spatial subregions in particular time intervals of interest in an unsteady flow field. Additionally, dye evolution is closely related to non-discrete particle residence time (PRT) calculations that are governed by similar PDEs. This contribution introduces a pseudo-spectral method based on Fourier continuation (FC) for conducting dye simulations and non-discrete particle residence time calculations without numerical diffusion errors. Convergence and error analyses are performed with both manufactured and analytical solutions. The methodology is applied to three distinct physical/physiological cases: 1) flow over a two-dimensional (2D) cavity; 2) pulsatile flow in a simplified partially-grafted aortic dissection model; and 3) non-Newtonian blood flow in a Fontan graft. Although velocity data is provided in this work by numerical simulation, the proposed approach can also be applied to velocity data collected through experimental techniques such as from particle image velocimetry.