Transient flow analysis, such as wind load testing, has historically been fraught with lengthy timelines and high up-front costs in order to yield realistic results. Yet, CFD engineers no longer need to choose between speed and accuracy. Follow us on LinkedIn: https://www.linkedin.com/company/simscale-gmbh/ And subscribe to our YouTube for more videos: https://www.youtube.com/channel/UCIi21t-7PVPNECXeAS0z7pw

1. Pacefish® on SimScale
Introducing the First LBM Flow Solver on SimScale

2. Why?
Monthly Simulation Jobs on SimScale
Why is SimScale integrating a new solver?

3. Why?
Why is SimScale integrating a new solver?
General FEA
General CFD
Code_Aster
Implicit FEM Solver
→ Continued investment
OPENFOAM®*
Finite Volume Solver
→ Continued investment
*This offering is not approved or endorsed by OpenCFD Limited, producer and distributor of the OpenFOAM software
via www.openfoam.com, and owner of the OPENFOAM® and OpenCFD® trade marks.
Next?
Transient? Fast? Robust?
...

4. Introducing Pacefish
● Developed by Numeric Systems GmbH
● Solver using Lattice Boltzmann method
● Multi-GPU enabled
● Fully integrated into SimScale
● Turbulence models: Smagorinsky (LES)
● SST-DDES and SST-IDDES (uRANS-LES)
and k-omega SST (uRANS)
Enabling accurate, fast and robust aerodynamics.

5. Pedestrian Wind Comfort Assessment
Ground Transportation Aerodynamics
Building Wind Load Prediction
General Wind Engineering
Applications
So what can I do with it?
● External aerodynamics tailored
● Unsteady by definition
● Isothermal & incompressible
● Turbulence profile definition
● Various post-processing
Initial Release:

6. Live Demo
Enough talk. Let’s see GPU-based LBM in action!
● CAD Import
● Domain Definition
● Physics Setup
● Post-Processing

7. Characteristics
Why should I care about this?
Accurate
Enables massive scale combined with
sophisticated turbulence modeling.
Fast
GPU implementation enables extremely quick
turnaround times for massive problems.
Robust
Handles dirty CAD gracefully, no explicit
CAD clean-up required.

8. Accuracy
Example Validation Projects
Cylinder Flow
Ahmed Body
CAARC Building

9. Cylinder Flow
Validation Projects – Example 1
Flow Scenario
● Re = 3900
● Velocity inlet: 0.59 m/s
● Kinematic viscosity: 1.511 x 10-5 Kg/m.s
● Density: 1 Kg/m3
Validation Results
● Circumferential mean pressure distribution
● Averaged values of the last 20% of the simulation
● Compared with [1], [2] and [3]
1. Norberg, ‘Effects of Reynolds number and low-intensity free stream turbulence on the flow around a circular cylinder’, Publ. No. 87 /2, Department of Applied Thermoscience and Fluid Mech., Chalmers University of Technology, Gothenburg, Sweden, 1987.
2. Ong and J. Wallace, ‘The velocity field of the turbulent very near wake of a circular cylinder’, Exp. Fluids, 20, 441–453, Springer Verlag, Berlin (1996).
3. L.M. Lourenco and C. Shih, ‘Characteristics of the plane turbulent near wake of a circular cylinder, a particle image velocimetry study’, Private Communication, 1993.

10. Cylinder Flow
Validation Projects – Example 1
Instantaneous flow field along the stream and span-wise direction.
Comparison for Coefficient of Pressure obtained with different approaches.

11. Ahmed Body
Validation Projects – Example 2
[1] S.R. Ahmed, G. Ramm, Some Salient Features of the Time-Averaged Ground Vehicle Wake, SAE-Paper 840300, 1984
[2] Serre, Matthieu Minguez, Richard Pasquetti, Emmanuel Guilmineau, Gan Bo Deng, Michael Kornhaas, Michael Schäfer, Jochen Fröhlich, Christof
Hinterberger, Wolfgang Rodi, On simulating the turbulent flow around the Ahmed body: A French–German collaborative evaluation of LES and DES.`
Comparison for Drag coefficients obtained with different approaches.

12. Wind Direction
Face 2
Face 3
Face 4
Face 1
Row 1
𝞫
x
z
x’
y
’
z
CAARC Building 1
Validation Projects – Example 3
[1] Calin Dragoiescu, Jason Garber and Suresh Kumar (2006) ‘A Comparison of Force Balance and Pressure Integration Techniques for Predicting Wind-Induced Responses of Tall Buildings’.

13. CAARC Building 1
Validation Projects – Example 3
Overturn moment (CMx)
Overturn moment (CMy)
Torsion moments (CMz)
Basemeanoverturnmomentcoef.Basemeanoverturnmomentcoef.Basemeantorsionmomentcoef.
Instantaneous and time averaged velocity fields near the base of the tower.

14. Speed
What do you mean by “fast”?
(RANS,15mcells,4GPUs)
(LES,1.7mcells,64CPUs)
[1] Lipecki T., Bec J., Blazik-Borowa E.: “Surface pressures on rectangular cylinders – the dependence on aspect ratio, wind structure and angle of wind attack”, The Seventh
International Colloquium on Bluff Body Aerodynamics and Applications (BBAA7) Shanghai, China; September 2-6, 2012

15. Robust
Gracefully deal with dirty CAD

16. Robust
Gracefully deal with dirty CAD

17. Robust
Gracefully deal with dirty CAD

18. Wrap-up
Why should I care about this?
Accurate
Enables massive scale combined with
sophisticated turbulence modeling.
Fast
GPU implementation enables extremely quick
turnaround times for massive problems.
Robust
Handles dirty CAD gracefully, no explicit
CAD clean-up required.