To enable real-time simulations of thermal flows Johannes Sjölund has performed his master thesis at RISE SICS North during the spring. The purpose of the master thesis is to investigate the usage of the Lattice Boltzmann Method (LBM) of Computational Fluid Dynamics (CFD) for real-time simulation and prediction of indoor air flows inside a data center module.

To perform the simulation a program called RAFSINE was used, written by Nicholas Delbosc at the University of Leeds, which implemented LBM on Graphics Processing Units (GPUs) using NVIDIA CUDA. The program used the LBM model called Bhatnagar-Gross-Krook (BGK) on a three-dimensional lattice and had the capability of executing thermal simulations in real-time or faster than real-time.

A simulation model was developed describing the geometry, temperatures and air flows of an experimental data center module at RISE SICS North in Lule ̊a, Sweden, based on measurements and equipment specifications. The thermal model could be validated by comparing it with measurements recorded from sensors mounted in the experimental data center.

The thermal prediction was found to be accurate on a room-level within ±1◦C when measured as the average temperature of the air returning to the heat-exchange cooling units, with a maximum error of ±2◦C on an individual basis. The thesis discusses possible sources of error and suggestions for model improvements.

In order to use the LBM CFD program even from hardware not equipped with NVIDIA GPUs it was deployed on a remote networked server accessed through Virtual Network Computing (VNC). Since RAFSINE featured interactive OpenGL based 3D visualization of thermal evolution, accessing it through VNC required use of the VirtualGL toolkit, which allowed fast streaming of visualization data over the network. The thesis describes the deployment of VirtualGL as well as some performance and usability enhancements made to the RAFSINE source code.