Fast Fluid Dynamics Model

Originating from the computer game industry, Fast Fluid Dynamics (FFD) is a faster alternative to Computational Fluid Dynamics (CFD) used for fluid flow simulation. Dr. Zuo developed the FFD model for indoor environment modeling in his Ph.D. thesis “Advanced Simulations of Air Distributions in Buildings” at Purdue University. Since then, he and many other researchers have extended the FFD model for both indoor and outdoor airflow simulation. This page summarizes the development of FFD model by the SBS Lab over the years.

• Data Center Airflow Management:

The FFD model is tailored for data center computer room airflow management with new modules added for data center applications. The figure on the right shows temperature contours of an example data center with varying supply flow air ratio produced by FFD simulations. The air ratio is defined as the ratio of the total supply flowrate to the total IT flowrate. It can be seen a high air ratio overcools the data center, but too low of an air ratio can lead to unwanted hot spots. The source code is publicly available here. It is also publicaly released in the Modelica Buildings library to support the coupled simulation of indoor airflow and HVAC systems. The FFD model is already adopted by Schneider Electric in their commerical data center tools. The research is described in this paper: X. Han, W. Tian, J. VanGilder, W. Zuo, C. Faulkner 2021. “An Open Source Fast Fluid Dynamics Model for Data Center Thermal Management.” Energy and Buildings, 230, pp. 110599.

• Coupled Simulation of Indoor Environment and Building HVAC and Control System:

A detailed room model was implemented in the open source Modelica Buildings library to enable the coupling of FFD with Modelica. This coupled model enables the co-simulation of airflow and HVAC system to study the optimal design and control of indoor environment. The coupled models are available at the Modelica Buildings library website. The research is described in this paper: W. Zuo, M. Wetter, W. Tian, D. Li, M. Jin, Q. Chen 2016. “Coupling Indoor Airflow, HVAC, Control and Building Envelope Heat Transfer in the Modelica Buildings Library.” Journal of Building Performance Simulation, 9(4), pp. 366-381.

• Simulation of Outdoor Airflow Around Buildings:

FFD was compared to CFD for its ability to simulate natural ventilation in buildings, an important application to saving energy in buildings. The results showed that FFD could predict wind-driven and buoyancy-driven ventilation with reasonable accuracy. The figure on the right shows the velocity contours predicted by CFD (left) and FFD (right) for wind-driven ventilation around a group of buildings, where the prevailing wind is from the southwest direction (lower-left in the figure). The flow upstream is similar between the two, however discrepancies are present for the wake region behind the buildings. This research is described in this paper: M. Jin, W. Zuo, Q. Chen 2013. “Simulating Natural Ventilation in and Around Buildings by Fast Fluid Dynamics.” Numerical Heat Transfer, Part A: Applications, 64(4), pp. 273-289.

• Cross-platform Parallel Computing for Indoor Airflow Simulation:

Dr. Zuo implemented our first parallel verion of FFD in CUDA on a NVIDA GPU in 2009 and achieved 30 times speedup. Our latest parallel version of FFD code was implemented in OpenCL, which is a cross-platform parallel computing language. This code can perform parallel computing on multiple different CPUs or GPUs and achieved up to 1,000 times speedup as described in this paper: W. Tian, T. A. Sevilla, W. Zuo 2017. “A Systematic Evaluation of Accelerating Indoor Airflow Simulations Using Cross Platform Parallel Computing.” Journal of Building Performance Simulation, 10(3), pp. 243-255.

Open Source Release

• FFD code for data center airflow simulation: https://bitbucket.org/sbslab-zuo/ffd/src/master/.
• The mesh tool “SCI” program for Fast Fluid Dynamics in Modelica Buildings Library: https://github.com/FastFluidDynamics/Mesh.

Tutorial

• This guide demonstrates how to compile the FFD CPU and GPU codes in Windows.
• A guide for pre-processing with SCI can be found here.

Game Style Demo of FFD Code

Screenshot of Velocity Window	Screenshot of Contaminant Concentration Window	Screenshot of Temperature Contour Window

A game style demo of mixed convection flow in an empty room was created. Like playing a computer game, this interactive demo allows users to change supply airflow rate and floor temperature, add contaminants into the space and observe the transmission of the contaminants.

This demo can be downloaded here. It includes 1) Mixed_Convection_With_Control.exe which is executable file of FFD; 2) glut32.dll, which is a graphics library for visualization. The results have been validated in our paper: W. Zuo, Q. Chen 2009. “Real Time or Faster-than-Real-Time Simulation of Airflow in Buildings.” Indoor Air, 19 (1), pp. 33-44.

Commands for the Demo:

• To run “Mixed_Convection_With_Control.exe ” = double click the program
• To reset to the default condition = press “0” key
• To change the visualization window to “Velocity vector” = press “1” key
• To change the visualization window to “Contaminant Concentration” = press “2” key
• To change the visualization window to “Temperature Contour” = press “3” key
• To add force in the flow field = press and hold left mouse key in desired position
• To add smoke in “Concentration” window = press and hold right mouse key in desired position
• To make the velocity lines longer = press “l” key
• To make the velocity lines shorter = press “k” key
• To increase the floor temperature  = press “h” key
• To decrease the floor temperature = press “c” key
• To increase the supply airflow speed = press “f” key
• To decrease the supply airflow speed = press “s” key
• To quit = press “q” key

Related Journal Papers

• C. A. Faulkner, D. S. Jankowski, J. E. Castellini Jr., W. Zuo, P. Epple, M. D. Sohn, A. T. Z. Kasgari, W. Saad 2023. “Fast Prediction of Indoor Airflow Distribution Inspired by Synthetic Image Generation Artificial Intelligence.” Building Simulation, pp.1-20.
• X. Han, W. Tian, J. VanGilder, W. Zuo, C. Faulkner 2021. “An Open Source Fast Fluid Dynamics Model for Data Center Thermal Management.” Energy and Buildings, 230, pp. 110599.
• W. Tian, X. Han, W. Zuo, Q. Wang, Y. Fu, M. Jin 2019. “An Optimization Platform Based on Coupled Indoor Environment and HVAC Simulation and Its Application in Optimal Thermostat Placement.” Energy and Buildings, 199, pp. 342-251.
• W. Tian, J.W. VanGilder, X. Han, C.M. Healey, M.B. Condor, W. Zuo 2019. “A New Fast Fluid Dynamics Model for Data-Center Floor Plenums.” ASHRAE Transactions, 125, pp. 141-148.
• W. Tian, X. Han, W. Zuo, M. Sohn 2018. “Building Energy Simulation Coupled with CFD for Indoor Environment: A Critical Review and Recent Applications.” Energy and Buildings, 165, pp.184-199.
• W. Tian, T. A. Sevilla, D. Li, W. Zuo, M. Wetter 2018. “Fast and Self-Learning Indoor Airflow Simulation Based on In Situ Adaptive Tabulation.” Journal of Building Performance Simulation, 11(1), pp. 99-112.
• W. Tian, T. A. Sevilla, W. Zuo, M. Sohn 2017. “Coupling Fast Fluid Dynamics and Multizone Airflow Models in Modelica Buildings Library to Simulate the Dynamics of HVAC System.” Building and Environment, 122, pp. 269-286.
• W. Tian, T. A. Sevilla, W. Zuo 2017. “A Systematic Evaluation of Accelerating Indoor Airflow Simulations Using Cross Platform Parallel Computing.” Journal of Building Performance Simulation, 10(3), pp. 243-255.
• W. Zuo, M. Wetter, W. Tian, D. Li, M. Jin, Q. Chen 2016. “Coupling Indoor Airflow, HVAC, Control and Building Envelope Heat Transfer in the Modelica Buildings Library.” Journal of Building Performance Simulation, 9(4), pp. 366-381.
• M. Jin, W. Zuo, Q. Chen 2013. “Simulating Natural Ventilation in and Around Buildings by Fast Fluid Dynamics.” Numerical Heat Transfer, Part A: Applications, 64(4), pp. 273-289.
• M. Jin, W. Zuo, Q. Chen 2012. “Improvement of Fast Fluid Dynamics for Simulating Airflow in Buildings.” Numerical Heat Transfer, Part B Fundamentals, 62(6), pp. 419-438.
• W. Zuo, M. Jin, Q. Chen 2012. “Reduction of Numerical Diffusion in FFD Model.” Engineering Applications of Computational Fluid Mechanics, 6(2), pp. 234-247, 2012
• W. Zuo, Q. Chen 2010. “Fast and Informative Flow Simulation in a Building by Using Fast Fluid Dynamics Model on Graphics Processing Unit.” Building and Environment, 45(3), pp. 747-757.
• W. Zuo, J. Hu, Q. Chen 2010. “Improvements on FFD Modeling by Using Different Numerical Schemes.” Numerical Heat Transfer, Part B: Fundamentals, 58(1), pp. 1-16.
• W. Zuo, Q. Chen 2010. “Simulations of Air Distribution in Buildings by FFD on GPU.” HVAC&R Research, 16(6), pp. 785-798.
• W. Zuo, Q. Chen 2009. “Real Time or Faster-than-Real-Time Simulation of Airflow in Buildings.” Indoor Air, 19 (1), pp. 33-44.

Related Conference Proceedings

• C. A. Faulkner, D. S. Jankowski, W. Zuo, P. Epple, M. D. Sohn 2021. “A Novel Physics-informed Algorithm for Training AI Models to Predict Indoor Airflow.” Proceedings of the 12th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC 2021), Seoul, South Korea (Virtual Conference), November 24-26, 2021.
• X. Han, W. Tian, W. Zuo, J.W. VanGilder 2019. “Optimization of Workload Distribution of Data Centers Based on a Self-Learning In Situ Adaptive Tabulation Model.” Proceeding of the 16th Conference of International Building Performance Simulation Association (Building Simulation 2019), September 2-4, Rome, Italy.
• W. Tian, J.W. VanGilder, M.B. Condor, X. Han, W. Zuo 2019. “An Accurate Fast Fluid Dynamics Model for Data Center Applications.” The Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm 2019), May 28-31, Las Vegas, NV.
• W. Tian, Y. Fu, Q. Wang, T. A. Sevilla, W. Zuo 2018. “Optimization on Thermostat Location in an Office Room Using the Coupled Simulation Platform in Modelica Buildings Library: A Pilot Study.” Proceedings of the 4th International Conference on Building Energy and Environment (COBEE2018), pp. 569-574, February 5-9, Melbourne, Australia.
• W. Tian, W. Zuo, T. A. Sevilla, M. Sohn 2017. “Coupled Simulation Between CFD and Multizone Models Based on Modelica Buildings Library to Study Indoor Environment Control.” Proceedings of the 12th International Modelica Conference, pp. 55-61, May 15-17, Prague, Czech Republic.
• D. Li, W. Tian, W. Zuo, M. Wetter 2016. “Simulation Using In Situ Adaptive Tabulation and Fast Fluid Dynamics.” Proceedings of the ASHRAE and IBPSA-USA SimBuild 2016: Building Performance Modeling Conference, pp. 65-71, August 8-12, Salt Lake City, UT.
• W. Zuo, M. Wetter, D. Li, M. Jin, W. Tian, Q. Chen 2014. “Coupled Simulation of Indoor Environment, HVAC and Control System by Using Fast Fluid Dynamics and the Modelica Buildings Library.” Proceedings of the 2014 ASHRAE/IBPSA-USA Building Simulation Conference, pp. 56-63, September 10-12, Atlanta, GA.
• M. Jin, Q. Chen, and W. Zuo 2013. “Validation of a Fast Fluid Dynamics Program for Simulating Natural Ventilation in Buildings.” Proceedings of CLIMA 2013, the 11th REHVA World Congress and the 8th Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings, June 16-19, Prague, Czech.
• M. Jin, W. Zuo, Q. Chen 2012. “Validation of Three Dimensional Fast Fluid Dynamics for Indoor Airflow Simulations.” Proceedings of the 2nd International Conference on Building Energy and Environment (COBEE2012), pp. 1055-1062, August 1-4, Boulder, CO.
• W. Zuo, Q. Chen 2011. “Validation of a Fast-Fluid-Dynamics Model for Predicting Distribution of Particles with Low Stokes Number.” Proceedings of the 12th International Conference on Indoor Air Quality and Climate (Indoor Air 2011), June 5-10, Austin, TX.
• W. Zuo, Q. Chen 2010. “Fast Simulations of Smoke Transport in Buildings.” Proceedings of the 41st International HVAC&R congress, pp. 340-348, December 1-3, Beograd, Serbian.
• J. Hu, W. Zuo, Q. Chen 2010. “Impact of Time-Splitting Schemes on the Accuracy of FFD Simulations.” Proceedings of the 7th International Indoor Air Quality, Ventilation and Energy Conservation in Buildings Conference (IAQVEC 2010), August 15-18, pp. 55- 62, Syracuse, NY.
• W. Zuo, Q. Chen 2010. “Improvements on the Fast Fluid Dynamic Model for Indoor Airflow Simulation.” Proceedings of the 4th National Conference of International Building Performance Simulation Association -USA (SimBuild2010), pp. 539-546, August 11-13, New York, NY.
• W. Zuo, Q. Chen 2009. “High-Performance and Low-Cost Computing for Indoor Airflow.” Proceedings of the 11th Conference of International Building Performance Simulation Association (Building Simulation 2009), pp. 244-249, July 27-30, Glasgow, U.K.
• W. Zuo, Q. Chen 2009. “Fast Parallelized Flow Simulations on Graphic Processing Units.” Proceedings of the 11th International Conference on Air Distribution in Rooms (RoomVent 2009), May 24-27, Busan, Korea.
• W. Zuo, Q. Chen 2007. “Real Time Airflow Simulation in Buildings.” Proceedings of the 6th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings (IAQVEC 2007), October 28-31, Sendai, Japan.
• W. Zuo, Q. Chen 2007. “Validation of Fast Fluid Dynamics for Room Airflow.” Proceedings of the 10th Conference of International Building Performance Simulation Association (Building Simulation 2007), pp. 980-983, September 3-6, Beijing, China.