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#1 |
New Member
Ewan k
Join Date: Jun 2022
Posts: 1
Rep Power: 0 ![]() |
Hi, im very new to openfoam and am struggling to get my head round some problems.
for context, im working on a masters Diss covering altitude compensating nozzles and i need to be able to run simulations of a bell nozzle and aerospike at different altitudes/atmo pressure, including vacuum opperation. currently i have played with sonicfoam, rhopimplefoam, and rhocenteral foam but each has given different errors. so a couple of questions i have are: -for my case, what would be the best solver? -and how should i go about setting this up, i.e. boundary conditions etc. the first nozzle is based off a chamber pressure of 9720000Pa at a temp of 3600k and designed for 3km so roughly 70000Pa atmo, at 270k. see attached the mesh and domain that i created in fluent and converted over. |
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#2 |
Senior Member
Join Date: Apr 2020
Location: UK
Posts: 711
Rep Power: 14 ![]() |
I have run axisymmetric sonic jet simulations with rhoSimpleFoam, but this took quite a lot of effort to make it work. rhoPimpleFoam would probably have been more stable, but I didn't want to run a transient solver. In the end, I found the following boundary set-up worked for me, along with upwind schemes to start and some relaxation:
pressure: Code:
upStream { type uniformTotalPressure; p0 table ( ( 0 101325) ( 1000 150000) ( 2000 500000) ( 8000 $pInlet) (999999 $pInlet) ); } downStream { type totalPressure; p0 101325; value uniform 101325; } Code:
upStream { type zeroGradient; } downStream { type pressureInletOutletVelocity; value uniform (0 0 0); } PS the key was to ramp up the upstream pressure rather than just applying the full pressure at the start - that gave the pressure solver an easier time. Let us know how you get on, Ewan. |
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