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transient boundary condition(Transient profile) |
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May 30, 2011, 11:58 |
transient boundary condition(Transient profile)
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#1 |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 17 |
Dear friends
I have questions on transient boundary condition "In some cases boundary conditions arise from measurements or mathematical functions". My questions are : 1. Is it possible to calculate the mean value of the measurements or mathematical function at the inlet and middle of the fluid model? 2. If the inlet is transient ( example: pressure) , How to set up the outlet condition? (example : Mass flow rate). Will the outlet boundary condition (Mass flow rate) be a function or Number? Thank you Regards Govind |
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May 30, 2011, 20:20 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,700
Rep Power: 143 |
Q1: Yes, this is possible
Q2: You set the boundary conditions to match what you are modelling. |
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May 30, 2011, 22:29 |
transient analysis
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#3 | |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 17 |
Quote:
Thanks for your kind reply Can you please explain how to calculate the average value (example: Pressure) at the inlet or middle of the fluid model. 2. For example, I set step pulse pressure at the inlet and I set a function at the outlet ( example sinusoidal Mass flow rate or sinusoidal velocity) , How will this match? Thanks you Regards Govind |
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May 31, 2011, 08:23 |
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#4 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,700
Rep Power: 143 |
Use a CEL expression like areaAve(p)@inlet.
What do you mean by match? As it converges it will reduce the imbalances. If incompressible that means flow in equals flow out, regardless or pressure or flow rate. |
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June 2, 2011, 21:41 |
transient analysis
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#5 | |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 17 |
Quote:
My fluid flow is pulsatile flow. mean flow rate is 50ml/min. Density is 1040 kg/m^3 . The mass flow rate = density*flow rate. How do I give this pulsatile mass flow rate value at the outlet. Thank you Regards Govind |
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June 2, 2011, 23:17 |
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#6 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,700
Rep Power: 143 |
Use a CEL expression like if or step, or a 1D interpolation function. Then use the function/expression in the boundary condition.
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June 3, 2011, 00:22 |
transient analysis
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#7 |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 17 |
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June 3, 2011, 07:10 |
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#8 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,700
Rep Power: 143 |
Is this an external input, that is you specify the flow rate; or is this an output of the simulation?
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