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March 23, 2013, 01:38 |
Stagnation pressure
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#1 |
New Member
Anonymous 92
Join Date: Feb 2013
Posts: 18
Rep Power: 13 |
In my simulation of the flow around the Ahmed body to determine drag coefficient, at the front face, I am not getting the expected value of stagnation pressure. Any idea what could be the issue involved?
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March 23, 2013, 09:18 |
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#2 |
Senior Member
Vangelis Skaperdas
Join Date: Mar 2009
Location: Thessaloniki, Greece
Posts: 287
Rep Power: 21 |
what value do you get?
higher or lower than expected? http://www.cfd-online.com/Forums/ope...-than-one.html |
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March 23, 2013, 12:49 |
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#3 |
New Member
Anonymous 92
Join Date: Feb 2013
Posts: 18
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The pressure works out to be 1000 Pa higher than the expected value. What would you recommend for this case specifically since the Ahmed body analysis has been done over so many times. And yes, I'll read on that.
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March 26, 2013, 02:41 |
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#4 |
Senior Member
Vangelis Skaperdas
Join Date: Mar 2009
Location: Thessaloniki, Greece
Posts: 287
Rep Power: 21 |
Try expressing this value as static pressure coefficient.
This value should equal 1 at stagnation point. |
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March 26, 2013, 06:00 |
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#5 |
New Member
Anonymous 92
Join Date: Feb 2013
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I did. But I got a value close to 2 where it was supposed to 1.
My physical conditions with respect to pressure are Initial conditions Pressure - 101325 Pa Reference values Pressure - 101325 Pa Force coefficient report Reference pressure - 101325 Pa My inlet and outlet conditions are Velocity Inlet and Flow split outlet, respectively. I'm sorry but I'm still in the learning stages. Could you please help me out? |
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March 26, 2013, 06:14 |
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#6 |
Senior Member
Vangelis Skaperdas
Join Date: Mar 2009
Location: Thessaloniki, Greece
Posts: 287
Rep Power: 21 |
I am not familiar with StarCCM+ unfortunately.
My only guess would be to use another BC type for outlet like Pressure Outlet instead of Flow Split I am sure someone more familiar with Star can guide you good luck Vangelis |
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March 26, 2013, 07:15 |
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#7 |
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Anonymous 92
Join Date: Feb 2013
Posts: 18
Rep Power: 13 |
Ah, right. Still, thanks.
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March 27, 2013, 14:35 |
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#8 | |
Senior Member
Ryne Whitehill
Join Date: Aug 2009
Posts: 312
Rep Power: 18 |
Quote:
So when you set 101325 as your initial condition, you are setting the absolute pressure to 202650. Any pressure other than a "reference pressure" is understood to be <typed in value> + Reference Pressure |
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March 30, 2013, 01:09 |
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#9 |
New Member
Anonymous 92
Join Date: Feb 2013
Posts: 18
Rep Power: 13 |
Oh, yes. Can't believe I missed that. Thanks! Changed, and it's fine, now.
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