Modeling natural convection in water tank with heat exchanger
Hello! I'm modeling natural convection in water tank. Geometry is simple, big water tank with heat exchanger (represented by 5 toruses). I'm using 2D axisymmetric model. BC are:
inlet: water, temp. 12.5 C, mass flow inlet 0.17 kg/s
outlet: mass flow outlet 0.17 kg/s
wall heat exchanger: temp 80 C (constant temp.)
all other walls are heat flux = 0 W/m2
I included energy equation.
Gravity is turned on, 9.81 m/s in negative X direction.
Simulation time is STEADY!
I'm using boussinesq aproximation for modeling natural convection but there is a problem because my residuals are not converging and total heat fluxes are not zero (they are around 3 kW which is big error).
I'm using coupled scheme with PRESTO pressure and all 2nd Order Upwind spatial discretization.
Turbulence model is k-epsilon RNG
I tried changing everything, including models and schemes, changing controls and everything but nothing helps.
I will provide pictures of mesh and geometry: https://imgur.com/a/ulEHLHY