adiabatic surface BC

alpharays786

Hi,

 

In acusolve, which one is the correct setting to present adiabatic condition for surface BC?

 

a-> environment temp. = 25 degree C

    Temperature BC type = Value

    Temperature = 25 degree C

 

or

 

b-> environment temp. = 25 degree C

    Temperature BC type = Flux

    Heat flux = 0.0

    Convective heat flux coefficient = 0.0

    Convective heat flux reference temperature = 0.0 degree C

 

c-> environment temp. = 25 degree C

    Temperature BC type = Flux

    Heat flux = 0.0

    Convective heat flux coefficient = 0.0

    Convective heat flux reference temperature = 25 degree C

 

Thanks

cfdguru

To model an adiabatic wall, you need to set all mechanisms of heat transfer to zero.  AcuSolve allows you to model various different heat transfer mechanisms on a given surface.  So, let's discuss the two that you are referring to separately.

 

The first mechanism is the heat transfer from the conduction and convection of the material adjacent to the wall that you are assigning boundary conditions to.  To zero this mechanism of heat transfer, you need to set temperature_type=flux, and heat_flux = 0.0. 

 

The second mechanism of heat transfer that AcuSolve supports on the surface is heat flux to the surroundings that are not present in the model.  Let's consider an insulated wall that is adjacent to a large room with a constant temperature.  In this case, it may be desirable to model the convection of the wall to the surroundings.  This can be accomplished by setting a convective heat flux coefficient and reference temperature.  The default setting of convective_heat_coefficient=0.0 ensures that this mechanism of heat transfer is disabled. 

 

So in your case, if you want the wall to be truly adiabatic, you will need to set heat_flux=0.0, and convective_heat_coefficient=0.0.  Note that when convective_heat_coefficient=0.0, the value specified for reference temperature is irrelevant.