I am doing research on the combined effect of natural convection and forced convection by providing velocity through ventilation ports in a rectangular enclosure keeping bottom plate heated at constant temperature. I want to find heat flux on hot plate maintaining at constant temperature in order to find heat transfer coefficient at different time. Please let me know that how to get rid of it in ANSYS Fluent.
P.S- Wall heat flux value through CFD-Post in ANSYS Fluent is giving much higher value.
There is a relationship between convection co-efficient vs. velocity for force convection i.e. 0.332*Re^0.33*Pr^0.33*K/t where, Re=Reynold's no., Pr= Prandtl no., K = thermal conductivity and t is thickness of boundary layer.
thank you for the reply. But this correlation won't work as Reynold number is fixed and i need to evaluate heat transfer at different time level at a particular Re. Inspite of this, it will be very helpful if you let me know that how Ansys calculate heat flux of a plate maintained at constant temperature condition.
Generally, heat flux is an input parameters in ansys. It is equal to heat (W)/area i.e. the unit of heat flux is W/m^2. To maintain a constant temperature you have to apply a constant heat-flux which should not change with time.
(In ANSYS there generally a film co-efficient or convection co-efficient is used. If it will be temperature dependent then you have to define the temperature dependent film co-efficient. )
sir if i'll be using constant heat flux then definitely temperature will be rising until the case has been reached its steady state otherwise it will violate energy conservation phenomenon. But here i need to keep the constant temperature at a particular value corresponding to that Rayleigh number. Meanwhile i want heat flux at different time step
As I understand u want wall surface temperature to be constant. In this case, the heat transfer coefficient can be calculated using bulk temperature of the fluid, by applying energy conservation i. e. hA(Tw-Tm)=mCp(del-T)fluid=Q. As (del-T)fluid will change for every time step, heat flux, as well as heat transfer coefficient can be calculated. At initial condition, you have to define the bulk temp of fluid, but after each time step the bulk temperature will increase untile you reached the study state.
As we are providing continuous supply of air in the enclosure so how do we calculate m ?
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