What exactly is h in externalWallHeatFluxTemperature BC?
Hi all!
Maybe it is a stupid question, but after looking into the code I'm still a bit confused about true meaning of h in the externalWallHeatFluxTemperature. If I assume the following boundary problem internal fluid -> wall -> environment there are two heat transfer coefficients coming into play - alpha_1 between the internal fluid and the wall and alpha_2 between the wall and the environment. So which one of these is h? |
Hi,
If you take a look at the sources, here's the way heat flux is calculated: Code:
case fixedHeatTransferCoeff: 1/h = 1/h_{flud->wall} + 1/h_{wall} + 1/h_{wall->external} |
Hi Alexey,
thanks for the reply. I'm using OF v 2.3.x with a little bit different code Code:
if (thicknessLayers_.size() > 0) Code:
else if (mode_ == fixedHeatTransferCoeff) Quote:
1/h_{wall} = totalSolidRes so I presume 1/h_ = 1/h_{fluid->wall} + 1/h_{wall->external} I suppose I have to estimate the 1/h_{fluid->wall} for example from https://upload.wikimedia.org/math/0/...1b1947b758.png as mentioned in https://en.wikipedia.org/wiki/Heat_transfer_coefficient and then do a similar thing for 1/h_{wall->external} to get the h_ for input of the boundary condition... |
After looking into code of mixedFvPatchScalarField and fluidThermo I think I got it. The h_ is the outer heat transfer coefficient - the 1/h_{wall->external}.
Heat transfer from internal fluid -> wall is solved using the kappa() field, inside the wall with the use of totalSolidRes which leaves the h_{wall->external} to be set by the user. |
Exactly Petr, h is the external heat transfer coefficient, the value of the solid resistance is calculated if you provide values of the kappa layers and thickness layers, otherwise it's neglected.
Regards, Alex |
Quote:
|
All times are GMT -4. The time now is 14:21. |