adiabatic wall boundary condition

- February 12, 2019 at 5:41 pm
  
  Weiqiang Liu
  Subscriber
  
  hello, all
  
  I have a channel with catalyst on the wall. I want set adiabatic condition of the wall to the environment. However, in the thermal condition panel of fluent for the wall, there are several options like : heat flux, temperature, convection, radiation, mix.
  
  I am wondering if I set the heat flux or convection coefficient to 0 in order to indicate adiabatic condition to environment. How does the heat produced on the wall transfer to inner gas flow. Because the heat flux on the wall is zero or the convection coefficient of the wall is 0. No heat flux is going to happen along the wall nodes.
  
  below is my mesh. I don't have solid computation domain.
  
  Thanks very much!
  
  weiqiang
- February 12, 2019 at 6:08 pm
  
  Amine Ben Hadj Ali
  Ansys Employee
  
  wall heat flux =0 refers to the adiabatic wall. There is no heat transfer to the fluid. The temperature at the wall is equal to the near wall cells. Heat release due to surface reaction are ingored by Fluent (default behavior). I guess if activated it will dump heat to the next cell. Just try and report.
- February 12, 2019 at 6:47 pm
  
  Weiqiang Liu
  Subscriber
  
  if there is no heat transfer to the fluid. Then what kind of thermal boundary condition should I give to give. Because heat produced on the wall surely would be transported to the fluid to heat the gas in real application.
  
  am I right?
- February 12, 2019 at 7:35 pm
  
  Amine Ben Hadj Ali
  Ansys Employee
  
  I will think that the heat is dumped into the next cell layer even if the wall is adiabatic. Just give it a try as I am not pretty sure here.
- February 12, 2019 at 8:54 pm
  
  Weiqiang Liu
  Subscriber
  
  yes, according to my results, the heat is dumped into the next cell layer when the wall is adiabatic. I guess adiabatic of the wall means there is no temperature gradient to the outside of the wall, however temperature gradient exists towards the fluid flow?
- February 12, 2019 at 10:26 pm
  
  Amine Ben Hadj Ali
  Ansys Employee
  
  What I suspected: yes.
- December 29, 2022 at 8:40 pm
  
  Ahmad Malekshahi
  Subscriber
  
  Zero heat flux in a wall means insulation not zero heat transfer. When heat flux is zero at a boundary it means that conduction heat transfer is zero but convection heat transfer is not necessarily zero because while there is temperature difference between wall and fluid convection heat transfer occurs but heat transfer in form of conduction through the wall from outside into inside or inside onto outside is zero. This is the meaning of zero heat flux.