The University of Southampton
Engineering and the Environment

Research project: Accurate Cartesian-grid modeling of unsteady and separating flows

Currently Active: 

A novel Cartesian-grid approach is developed to accurately model forces and separation on complex moving geometries such as swimming animals.

Project Overview

Immersed Boundary (IB) methods enable simulating flows with complex geometries and moving boundaries, but have known issues with non-physical near-wall predictions. A new approach called the Boundary Data Immersion Method (BDIM), is less ad-hoc, second-order, and has been shown to produce accurate near wall predictions for moving bodies and separating flows. This technique has been applied to a variety of complex fluid structure interaction problems such as the swimming of animals (from stingrays to dinosaurs) and the fluid structure interaction of marine structures.

An open source version of this numerical method has been developed called Lily Pad. This software is simple and user friendly; lowering the boundary to accurate CFD simulations for research, teaching, and design. 

Numerical method comparison

The image to the right compares the vorticity field past a slender foil using standard first-order IB methods and the new second-order BDIM. The IB method predicts spurious separation on the foil, while the BDIM simulation match experiments and fitted grid simulations.


BDIM simulation of a swimming stingray (below).
The vortex cores in the wake are shown, color by
vorticity around the lateral axis.

Associated research themes

Fluid dynamics

Related research groups

Fluid Structure Interactions


Key Publications


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