MRFSimpleFoam and BCs
Dear all,
I have some questions regarding a simple case for MRFSimpleFoam. I have a cylindrical domain in which one side is inlet, the other is outlet and in it there is a small fan that is rotating. Ideally, I want to let the fan determine the input flowfield. For this problem I used laminar flow which I plan to change it to turbulent when the inlet velocity is determined. I tried to use the following boundary conditions: Inlet U: zeroGradient p: zeroGradient Outlet U: zeroGradient p: fixedValue Walls U: fixedValue 0 p: zeroGradient With the above settings I cannot get convergence and in the flow field there are backflows happening in various areas of the domain, which seems logical due to U zeroGradient at inlet and outlet. I also tried to use pressureInletVelocity for U at the inlet but the results were worse. If I impose U: fixedValue at the inlet, then everything works and I get convergence quite quickly. Any ideas on this? |
hi
have you been able to solve that? |
I was able to solve the problem only when I had defined an inlet velocity.
I have not been able to solve the case if I want the fan to determine the inflow. |
hi can you please explain to me how you had defined the inlet vel?
thnaks zaynah |
for the case that worked you can either define e.g.
inlet { type fixedValue; value uniform (1 0 0); } or inlet { type surfaceNormalFixedValue; refValue uniform -1; } both of the above work. |
the (1 0 0)
1 define 1m/s in x drection right? but what does the Quote:
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Quote:
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Pretty easy to let the fan determine the inflow.
U Code:
inlet Code:
inlet |
Linnemann thank you very much.
totalPressure and pressureInletVelocity worked very well. Maybe I could have realized it after studying a little more the manual. From what I understand, totalPressure BC is linked with pressureInletVelocity, pressureInletOutletVelocity, etc conditions or the opposite? |
Hi Linnemann,
The explained boundary conditions are fine, but i have small doubt. how to define are where to define the quantity of the flow. If i want to define 5 m3/s. how to define this with the above given example BC. Thanks, Aadhavan |
Hi
With the above BC's you cant define the volume flow. Then you switch to the below BC's U Code:
inlet Code:
inlet |
Hi Linnemann,
Thanks for your reply, This BC already i am using. I want to use pressureInletVelocity BC, if I use this, how can I understand that, at what flow rate it is the simulation is going on. in my case the fan is designed for 5m3/s, if I want to see the performance at different flowRate, can I use this BC (pressureInletVelocity), if so how can I implement it. thanks, Aadhavan |
2 Attachment(s)
Quote:
Hi Linnemann, i have some doubts with the U value of inlet. if write it like : type fixedValue; value uniform (0.5 0 0); OK? if i have a model like this: inlet U=0.5, outlet contact the atmosphere. the fluid flow from the inlet to the outlet. Attacted are the Pd and U , run the interFoam, wrong... can you give me some advises?Attachment 17248 Attachment 17249 |
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