icoFoam Blowup at Farfield Boundary
 

Hello,


I am running a transient Karman-Trefftz airfoil case with icoFoam.


Re: 10000
α: 5°
Grid Topology: O
Number of Cells: ~1000000 (almost entirely perfect squares)

Δt: 0.0004

Domain Radius: 20c
Wall BC: zeroGradient Pressure, noSlip Velocity

Farfiled BC: fixedValue Pressure, fixedValue Velocity



I know this isn't the ideal setup for this problem but I am just trying to experiment. The max Courant number starts off a bit high for a few steps near the LE and TE where the cells are smallest, but it quickly settles into about 0.8 as the boundary layer grows. On the downstream boundary, a wavy artifact in the velocity field starts off barely visible and then gradually grows until the solution blows up.


t=0.4s
Attachment 88528


t=6.0s
Attachment 88529


t=7.6s
Attachment 88530


Is there something wrong with my boundary conditions?

Solved


I managed to stabilize it by changing the farfield boundary conditions to freestreamVelocity and freestreamPressure.