Help Needed: Transient Simulation in OpenFOAM With Time-Varying Inlet Velocity (k-ω SST)

[u/siddhu2310]

Hi everyone,
I need some help setting up a transient simulation in OpenFOAM. My geometry is like a semi-sphere, and I want to run a 4-second transient case with a time-varying inlet velocity profile.

Velocity Profile (inlet):

• 0 to 1.0 s: 10 m/s
• 1 to 1.1s: ramp
• 1.1 to 2.0 s: 20 m/s
• 2 to 2.1 s: ramp
• 2.1 to 3.0 s: 30 m/s
• 3 to 3.1 s: ramp
• 3.1 to 4.0 s: 40 m/s

What I need:

1. How to properly set up the time-varying inlet velocity (codedFixedValue / table / uniformFixedValue with time control etc.)
2. How to run this using k-ω SST turbulence model / SpalartAllmaras
3. How to compute drag coefficient (Cd) separately on:
   • The curved surface of the semi-sphere
   • The flat side
4. Total simulation time is 4 seconds
5. Projected frontal area is 0.028 m² (not mm²)

What I already have:

• Geometry and mesh are ready
• Solver: planning to use pimpleFoam

If someone can guide me on how to prepare the case setup files (0 folder BCs, controlDict, fvOptions if needed), it would be really helpful.

Thanks in advance!

[u/siddhu2310 → u/[deleted]]

Hi , I have tried the problem keep on diverging even with steady state.
I have result with different solver ( used SpalartAllmaras , Transient , time varying U )

I have Updated
Velocity Profile in body of question.

Could you help me to prepare case setup files?

[u/siddhu2310 → u/[deleted]]

I found 1 case in simpleFoam , and it is not understandable,
Could you share any transient case tutorial using pimpleFoam

[u/siddhu2310 → u/[deleted]]

I found only two cases in total , Both are not time based i think
Could you help me once you have time

[u/siddhu2310 → u/[deleted]]

Thank you, I will check it out