ATOMS Laboratory | Advanced Thermal/Fluid Optimization, Modelling and Simulation Laboratory

Fluid Flow Simulation in Complex Systems

Our research lab has acquired an extensive expertise in numerical modelling of fluid flow and heat transfer in complex geometries using both conventional (Navier-Stokes based CFD methods) and novel (lattice Boltzmann method) numerical techniques. Our flow simulation efforts have focused on two main areas: haemodynamics of abdominal aortic aneurysms and flow in porous materials with application in fuel cells.

(1) Blood flow simulation in abdominal aortic aneurysms

We use imaging techniques to reconstruct the patient-specific geometries. The figure to the right shows a reconstructed 3D geometry of a cross-limb stent-graft device from patient-specific sliced CT Scan images. The reconstructed geometries are then used for our flow simulations using conventional CFD techniques. The figure below shows the predicted streamlines pattern in three different configurations of stent-grafts in an abdominal aortic aneurysm. The flow simulations are carried on in ANSYS CFX software, where physiologic pulsatile boundary conditions are implemented. The cross-limb stent-graft configuration (centre) continuously shows distinctively different flow patterns at the graft outlets from the direct (left) and planar (right) configurations.

(2) Flow simulation in porous media with application to PEM fuel cells

We have used the lattice Boltzmann method (LBM) for flow simulation in various forms of porous media. The mesoscopic nature of the LBM along with the easy implementation of the solid wall boundary conditions make this approach a powerful tool for fluid flow simulation in complex geometries. The underlying micro-physics of complex systems can also be easily implemented in the LBM fluid flow simulations. Figure on the left shows a high porosity sample of the reconstructed fibrous medium, where the porosity of the sample is 0.80. Figure on the right shows the velocity vectors in a slice of a three-dimensional fibrous medium, which has a porosity equal to 0.2. The pressure gradient and the mean flow direction are in the positive x-direction.

(a) Reconstructed three-dimensional medium with straight fibres and porosity of 0.80. (b) Velocity vectors in a slice of the three-dimensional fibrous medium; the porosity of the sample is 0.2 and the pressure gradient drives flow in the positive x direction.