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10^3 temperature
Posted 13 lug 2017, 06:55 GMT-4 3 Replies
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Hi, I 'm having some temperature issues. I have a eletric motor cooling system, with water chanels.
And I'm reaching temperatures like 2x10^3 kelvin...
I used conjugate heat ( heat transfer and laminar flow) the heat source is the motor with an heat rate of 2000 W the initial value of temeprature is 303.15 K, and the inlet mass flow is 0.1 kg/s. I have also a convective heat flux with an heat transfer coefficient (h) of 25 W/(m^2*K) and external temperature of 303.15 K also.
Can someone explain me what's wrong?
And I'm reaching temperatures like 2x10^3 kelvin...
I used conjugate heat ( heat transfer and laminar flow) the heat source is the motor with an heat rate of 2000 W the initial value of temeprature is 303.15 K, and the inlet mass flow is 0.1 kg/s. I have also a convective heat flux with an heat transfer coefficient (h) of 25 W/(m^2*K) and external temperature of 303.15 K also.
Can someone explain me what's wrong?
3 Replies Last Post 13 lug 2017, 08:43 GMT-4
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Posted:
7 years ago
Hello
Without the model it's difficult, I would guess you have either a selection wrong, or a sign issue.
Another cause could be initial conditions too far from physical reality and the solver get crazy, that is easy in diffusion problems, particularly for time solving if you do not check your CFL values, and have a fine enough mesh where the initial temperature gradients are strong.
"My way" is to always run first "Get initial conditions" study these carefully, adapt if required, then solve with a PLOT WHILE SOLVING, often also deep down in the solver sub-nodes to have extensive plotting. That often gives you clues about what is going wrong
--
Good luck
Ivar
Without the model it's difficult, I would guess you have either a selection wrong, or a sign issue.
Another cause could be initial conditions too far from physical reality and the solver get crazy, that is easy in diffusion problems, particularly for time solving if you do not check your CFL values, and have a fine enough mesh where the initial temperature gradients are strong.
"My way" is to always run first "Get initial conditions" study these carefully, adapt if required, then solve with a PLOT WHILE SOLVING, often also deep down in the solver sub-nodes to have extensive plotting. That often gives you clues about what is going wrong
--
Good luck
Ivar
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Posted:
7 years ago
The study is in stationary mode. How can I send you the model? I really need to solve this problem
Thank you for your quick a useful answer
Thank you for your quick a useful answer
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Posted:
7 years ago
Hi
Well if its a rather confidential model you SHOULD NOT SEND IT (anywhere) !!
What I do in these cases is to remake a neutral model, with the same physics, to reproduce the issue, more than 50% of the time I then discover myself what is wrong.
Normally these "toy models" should take 5 min to build, they must be simple with only what you suspect is wrong. if still there is an issue you may upload the toy model here on the Forum and mostly someone comes and helps
--
Good luck
Ivar
Well if its a rather confidential model you SHOULD NOT SEND IT (anywhere) !!
What I do in these cases is to remake a neutral model, with the same physics, to reproduce the issue, more than 50% of the time I then discover myself what is wrong.
Normally these "toy models" should take 5 min to build, they must be simple with only what you suspect is wrong. if still there is an issue you may upload the toy model here on the Forum and mostly someone comes and helps
--
Good luck
Ivar