The first test case is the CERFACS CO-VO, already performed on many codes.

Definition

An isentropic vortex is simply moving to the east of a periodic square grid. With time. The flow is supposed inviscid Euler Equations.

CO-VO Parameters
Density1.1608 Kg/m3
Temperature300 Kelvins
Pressure10^5 Pascals
Circulation34.728
Radius0.005m
Convection speedUc = 170m/s (Mach 0.5)
Resolution64×64
Domain-0.05, 0.05 m

For further details on the initialization equations, download the Cerfacs technical report here.

LEOPARD-Fine
Vortex convected by LEOPARD, a LBM testbed from Cerfacs, 10th turnaround.

Secondary test: unaligned convection

In LBM, the streaming operator is aligned with the grid. Therefore a vortex convection from west to east is a very good situation: only one direction is really working.
The secondary test is simply a convection with an angle, exactly atan (1/10) / pi180. = 5,71059314 degree*.
Therefore, after 10 revolution, the vortex should still be in the center.
The only difference is a small velocity component to the Y direction (south to north).

Unaligned CO-VO
Convection speed xUc = 170m/s (Mach 0.5)
Convection speed yVc = 17m/s

Article originally written by Antoine Dauptain (CERFACS), research scientist focused on computer science and engineering topics for HPC.