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impeller rotation in 2D
Posted 1 déc. 2010, 03:55 UTC−5 4 Replies
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Hii,
I am trying to run a simple simulation that models an impeller's rotation in 2D using Rotating Machinery module. But it fails and gives error.
Fearture: Time dependent solver1
error: Failed to find consistent initial values
The model is attached here. Can someone help me out
I am trying to run a simple simulation that models an impeller's rotation in 2D using Rotating Machinery module. But it fails and gives error.
Fearture: Time dependent solver1
error: Failed to find consistent initial values
The model is attached here. Can someone help me out
Attachments:
4 Replies Last Post 1 déc. 2010, 05:11 UTC−5
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Posted:
1 decade ago
Hi
when I loaded the model the Flow continuity was not "on", you need to select the identity pair to get the boundary ID's filling the selection list
Then if I add an initial pressure of 1[atm] it solves for 1 step, but I also I needed to delete and reset the model (but I'm in 4.1 could be some compatibility issues)
I got somewhat further by adding some initial rotating flow, but as I'm not a CFD expert I'm not the quickest to find the "evident" flaw of these issues;)
Have you tried to add a smoother turn on of the rotation (adding a step function) this often helps for starting a system
And if leaving the initial pressure to "0", you could add one point with an absolute pressure value to fix "p"
--
Good luck
Ivar
when I loaded the model the Flow continuity was not "on", you need to select the identity pair to get the boundary ID's filling the selection list
Then if I add an initial pressure of 1[atm] it solves for 1 step, but I also I needed to delete and reset the model (but I'm in 4.1 could be some compatibility issues)
I got somewhat further by adding some initial rotating flow, but as I'm not a CFD expert I'm not the quickest to find the "evident" flaw of these issues;)
Have you tried to add a smoother turn on of the rotation (adding a step function) this often helps for starting a system
And if leaving the initial pressure to "0", you could add one point with an absolute pressure value to fix "p"
--
Good luck
Ivar
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Posted:
1 decade ago
I fixed the flow continuity and have tried after changing the pressure value in initial conditions but it didn't help. The advice of step function...I have not checked yet ..actually I don't know how and (where from) I can add that.
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Posted:
1 decade ago
Hi
try adding 1) a point on a corner with a 0 pascal pressure just to have a fixed point
then add a step function in the definitions sub-node and multiply your rotation speed by this time dependent step function. this makes the system at rest at t=0 and then ramping up the speed smoothly, you might need to play a little with the step time, try to plot the function
--
Good luck
Ivar
try adding 1) a point on a corner with a 0 pascal pressure just to have a fixed point
then add a step function in the definitions sub-node and multiply your rotation speed by this time dependent step function. this makes the system at rest at t=0 and then ramping up the speed smoothly, you might need to play a little with the step time, try to plot the function
--
Good luck
Ivar
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Posted:
1 decade ago
ahaa... Yes it works with fixing a pressure point. Thank You. The step is still not used. But I will try the step function as well to learn it