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March 6, 2012, 06:18 |
Square velocity profile
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#1 |
New Member
Anand Nadgire
Join Date: Mar 2012
Location: Pune
Posts: 4
Rep Power: 14 |
hi,
i want to create square velocity inlet profile in cfx please help me. |
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March 6, 2012, 07:20 |
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#2 |
Senior Member
Lance
Join Date: Mar 2009
Posts: 669
Rep Power: 22 |
You'll have to be a bit more specific than that. What have you tried so far?
Also, do you mean square in space (plug shape) or square in time (transient velocity profile)? A plug shape is obtained by setting the velocity components on the inlet to a fixed value, while a square in time can be created by step functions. |
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March 7, 2012, 01:02 |
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#3 |
New Member
Anand Nadgire
Join Date: Mar 2012
Location: Pune
Posts: 4
Rep Power: 14 |
thanks for reply.
i want square in time (transient velocity profile). the profile is attached here. please tell me about step function and how to obtain square velocity inlet profile. |
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March 7, 2012, 03:02 |
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#4 |
Senior Member
Lance
Join Date: Mar 2009
Posts: 669
Rep Power: 22 |
A very simple expression could be:
(step((t-0.1[s])/1[s])+step((0.3[s]-t)/1[s]))*1[m/s] which will give you a square between 0.1 and 0.3 s, with the magnitude 1 m/s. The argument inside the step function must be dimensionless. |
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March 28, 2012, 05:53 |
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#5 |
New Member
Anand Nadgire
Join Date: Mar 2012
Location: Pune
Posts: 4
Rep Power: 14 |
instead of step function i have created following expressions to have continuous square velocity profile
LIBRARY: CEL: EXPRESSIONS: Freq = 10 [rad s^-1] InVel = if (TimeConst<=0, 0.05, vmax) [m s^-1] TimeConst = sin(2*pi*Freq*t) vmax = 30 END END The Plot of 'InVel' give required velocity profile. i have used it for simple pipe flow and kept a monitoring point at inlet which shown correct profile velocity varying between 0-30m/s. but when i was using same functions for my project it is not giving same profile it is varying between 0-1.2m/s why such thing is happening. the geometry snap of my project is attached herewith. please help |
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March 28, 2012, 06:05 |
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#6 |
Member
arjun
Join Date: Oct 2011
Location: Tokyo, JAPAN
Posts: 66
Rep Power: 14 |
Check all Boundary conditions, and try for some other cases. and apply same BC to your project.
Best Luck. |
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