The Size of CV

sidharth9426 · September 11, 2015, 06:17

Hello Everyone,
I wanted to know the procedure for determining the size of control volume, for a vehicle on which the under hood thermal analysis is done. Only the air flow has to be simulated. The thermal boundary conditions are given.

Thanking You,
Sidharth.

me3840 · September 13, 2015, 20:11

The CV needs to be large enough such that the relevant physics are captured. For underhood cases this means the aero solution plays a key role and the CV must be relatively large.

sidharth9426 · September 13, 2015, 23:22

Hi,
Actually I wanted to know the how to decide the dimension of CV, I mean is there any thumb rule relation which are like, length of CV= X * length of the vehicle...
And similarly for top and side length of CV..

me3840 · September 14, 2015, 19:58

The rule of thumb depends on the physics. I mean, generally for aero simulations you will want 10 lengths downstream, 5 upstream, maybe 5 on the sides, but this will depend on the type of vehicle and also doesn't take into account that you're not doing an aero simulation.

sidharth9426 · September 14, 2015, 22:32

Yes, I am not doing any aero simulation. I am modelling air and the variation in temperature under the hood of the car.
I saw many technical papers, but the process of deciding size of CV was mentioned in none.
So if you can give some reference, it will be great help..

.

September 11, 2015, 06:17	The Size of CV	#1
sidharth9426 New Member Sidharth Join Date: Sep 2015 Posts: 29 Rep Power: 10	Hello Everyone, I wanted to know the procedure for determining the size of control volume, for a vehicle on which the under hood thermal analysis is done. Only the air flow has to be simulated. The thermal boundary conditions are given. Thanking You, Sidharth. Last edited by sidharth9426; September 11, 2015 at 12:43.

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September 13, 2015, 20:11		#2
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	The CV needs to be large enough such that the relevant physics are captured. For underhood cases this means the aero solution plays a key role and the CV must be relatively large.

September 13, 2015, 23:22		#3
sidharth9426 New Member Sidharth Join Date: Sep 2015 Posts: 29 Rep Power: 10	Hi, Actually I wanted to know the how to decide the dimension of CV, I mean is there any thumb rule relation which are like, length of CV= X * length of the vehicle... And similarly for top and side length of CV..

September 14, 2015, 19:58		#4
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	The rule of thumb depends on the physics. I mean, generally for aero simulations you will want 10 lengths downstream, 5 upstream, maybe 5 on the sides, but this will depend on the type of vehicle and also doesn't take into account that you're not doing an aero simulation.

September 14, 2015, 22:32		#5
sidharth9426 New Member Sidharth Join Date: Sep 2015 Posts: 29 Rep Power: 10	Yes, I am not doing any aero simulation. I am modelling air and the variation in temperature under the hood of the car. I saw many technical papers, but the process of deciding size of CV was mentioned in none. So if you can give some reference, it will be great help.. .