Temperature initial conditions at wall
 

I am simulating air forced convection and conduction on a dummy human head using conjugate heat transfer with good results compared to experiment. I am trying to use buoyantSimpleFoam solver without the conduction to faster the solving time and I want to define the initial temperature at the head and let the convection cooling down. At the moment, I have difficulty with the bc to set an initial temperature different from internal fields that will be overwrite during time. In 0/T folder I am using the wall bc to fixedValue which is working but not what I want. I have tried fixedGradient with initial temperature, zeroGradient with initial temperature but it doesn't work. I know, it seems very easy to implement but I have yet not find the right way to do it and any help will be very helpful.