Heat Transfer Coefficients in AcuSolve

ydigit

Did you know that AcuSolve offers three ways to calculate heat transfer coefficients (HTC)? 

1.direct : Physics based  (available via acuTherm)
2. user_ref_temp: Physics based with varying reference temperature  (available via acuTherm or "Calculate" in SL/HWCFD)
3.turb_wall: Turbulent wall based (available by default, if turbulent equation enabled)

1. (direct) HTC is computed as a function of surface_heat_flux and local wall temperature and varying reference temperature. 

????????????=???? / (????????????????_????????????????????−????????????????????)

Where, Q = local surface heat flux

Twall = local wall temperature
TRef_local = local reference temperature computed by AcuTherm at user specified “thermal layer edge
yplus
thermal_layer_edge_yplus = 1000.0 by default

 

2. (user_ref_temp) HTC is computed as a function of surface_heat_flux and local wall temperature, assuming constant reference temperature.
????????????=???? / (????????????????−????????????????????)

Where, Q = local surface heat flux

Twall = local wall temperature
TRef_= user reference temperature 

This method is recommended when comparing against experiments or other CFD codes, that use the same expression for calculation. It is recommended when a well defined reference freestream / bulk temperature is available.

 

3. (turb_wall) This method is  an  interesting aspect of AcuSolve. It is generally useful for Model_A vs Model_B kind of comparisons. It is based on turbulent flow field (based on a self similarity solution). It does not require thermal equation to be enabled, but turbulent equation has to be enabled. This method should not be used for mapping to structural solver or comparison with other codes. 

If turbulence equation is active, the output "surface_film_coefficient" is available by default for post processing in HyperWorks CFD or SimLab or plotting programs. 

 

#1 and #2 require the enable nodal output frequency as shown in the screenshot. 

Use of acuTherm is also shown in the screenshot. 

translate_to

taitherm writes out a Patran file that can used in TAITherm as input.

abaqus writes out CSV file compatible for structural solver like OptiStruct or Abaqus.

Summary: default #3 is only for A vs B comparison. #2 is used most often for comparison with other solvers/hand calculation or Thermal FSI/mapping. 

 

Jagan Adithya Elango

acuTherm -pb htcmap -osfs "convection_wall" -to csv -ts L -fct direct -tlyp 200

Could you please confirm if this an appropriate command for #1?

Thanks

acupro

Jagan_21383 said:

acuTherm -pb htcmap -osfs "convection_wall" -to csv -ts L -fct direct -tlyp 200

Could you please confirm if this an appropriate command for #1?

Thanks

That looks correct to me - if you want the local reference temperature where Y+ is 200.

Is it giving you some error?