2021-01-22T17:21:36.000-0500

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Simcenter STAR-CCM+ Application Specific Solutions

When exchanging thermal boundary conditions between simulations it’s common to use a temperature and a HTC.

When exchanging thermal boundary conditions between simulations it’s common to use a temperature and a HTC. Consider Newton's law of cooling:

q˙s′′=h(Ts−Tref)

The local surface heat flux, q˙s′′, and the surface temperature, Ts, and are known and for every choice of heat transfer coefficient, h, there is a reference temperature, Tref, that satisfies the equation.

In Simcenter STAR-CCM+ there are 4 different field functions for HTC,

To illustrate this, please see the attached testcase of a solid cube given a heat source of 1000W with radiation activated. In the example the surface integral of h(Ts−Tref) does add up to 1000W for LHTC and Y+HTC but not for HTC. If you add the contribution from HTC with the radiated heat flux you get to the desired 1000W.

For more information about the 4 different HTC's, please see the Theory section on Convection and the Field Function Reference.

For more information on coupling 2 thermal simulation with HTC's (can be other software as well), please see Exchanging Heat Transfer Coefficients.

q˙s′′=h(Ts−Tref)

The local surface heat flux, q˙s′′, and the surface temperature, Ts, and are known and for every choice of heat transfer coefficient, h, there is a reference temperature, Tref, that satisfies the equation.

In Simcenter STAR-CCM+ there are 4 different field functions for HTC,

- Local Heat Transfer Coefficient (LHTC)
- Specified y+ Heat Transfer Coefficient (Y+HTC)
- Heat Transfer Coefficient (HTC)
- Virtual Local Heat Transfer Coefficient (does not need the energy equation and will not be considered here)

- LHTC uses the temperature of the cell closest to the wall
- Y+HTC uses the temperature at a specified distance (y+). Needs y+ as input, default is 100
- HTC uses a user specified temperature. Needs temperature as input, default is 300K

To illustrate this, please see the attached testcase of a solid cube given a heat source of 1000W with radiation activated. In the example the surface integral of h(Ts−Tref) does add up to 1000W for LHTC and Y+HTC but not for HTC. If you add the contribution from HTC with the radiated heat flux you get to the desired 1000W.

For more information about the 4 different HTC's, please see the Theory section on Convection and the Field Function Reference.

For more information on coupling 2 thermal simulation with HTC's (can be other software as well), please see Exchanging Heat Transfer Coefficients.