LATTICE BOLTZMANN 3D FLOW SIMULATIONS IN A HEPA AEROSOL FILTER, ON A COMPUTING GRID
Advancing the chemical engineering fundamentals
Multifase Flows - III (T2-5c)
Keywords: CFD simulations, Lattice Boltzmann Method, Porous medium, Permeability, X-ray tomography
Recent progress in experimentation, especially in the macro and micro X-ray computed tomography, allow access to complex geometries encountered in various fields of chemical engineering. In the domain of unit operations, high energy setup (420 kV) may be operated on columns of 0.4 m diameter along heights of several meters with resolution ranging about 0.5 mm. In the domain of materials, X-ray micro tomography devices are commonly available at 100 kV energy to analyse samples up to 3.5 cm diameter with resolution around 5 microns.
Consequently, it is natural to look forward to more accurate descriptions of phenomena occurring in packed beds, fibrous media, metallic foams to name a few, which will lead to better design of elements, better efficiency and selectivity of chemical engineering processes in which they take part. Likely, the use of efficient computational fluid dynamic tools should help to reach these goals. However, the problem of incorporating these intricate geometries in simulation codes is challenging. Indeed, the numerical reconstructions of the 3D images from these tomographic measurements lead to large matrix of voxels which must be used as boundaries for the flows. Lattice Boltzmann methods can easily accommodate directly these matrices but requires large computing powers, only available on very expensive computers with shared memory.
Progress in production of CPU’s allows considering grid computing as a pragmatic solution to this computing power problem, while keeping the best of the inherently parallel structure of Lattice Boltzmann algorithms. A grid is a system that coordinates resources that are not subject to centralized control, using standard, open, general-purpose protocols and interfaces to deliver nontrivial qualities of service.
In this communication, the grid concerned is a set of around 50 common PC (CPU around 2-3 GHz, memory 512/1024 MB). We consider the deployment of a simple, in house, 3D lattice Boltzmann code on this grid to simulate a Stokes flow within a HEPA aerosol filter, in order to evaluate its permeability. The geometric structure of the filter is obtained with a Skyscan 1172 microtomograph as a 400 x 400 x 400 voxel matrice. Results are discussed and compared to literature results.
Presented Tuesday 18, 10:05 to 10:25, in session Multifase Flows - III (T2-5c).
