fix dragforce/field/compressible command

Syntax

fix ID group-ID dragforce/field/compressible style_keyword style_values region region-ID field_keyword field_value ...

Keywords from fix_dragforce_field plus

  • In addition the following keyword/value pairs are required

  • style_keyword = rho_file or SutherlandCoeff

rho_file value = filename
  filename = filename for reading density and temperature field data (string)
SutherlandCoeff_viscRef = viscosity at reference temperature
SutherlandCoeff_Tref = reference temperature
SutherlandCoeff_S = Sutherland temperature

Examples

fix  drag    all dragforce/field/compressible Schiller_Naumann &
    fluid_viscosity $*visc* fluid_density $*rhof* &
    region reg &
    binsize 0.1 file data/test_field_U.dat &
    file_coords cod_U.dat interpolate yes &
    rho_file data/test_field_rho.dat &
    SutherlandCoeff_viscRef 1.716e-5 SutherlandCoeff_Tref 273.15 SutherlandCoeff_S 110.4

Description

Performs the same operations as fix_dragforce_field but uses a density and a temperature field which may vary in space (instead of a constant density). An example for the file format is given below:

x y z   rho_fluid 1 temp_fluid 1
-0.500000 -0.500000 0.500000  1.1  300.
-0.500000  0.500000 0.500000  1.1  300.
 0.500000 -0.500000 0.500000  1.2  290.
 0.500000  0.500000 0.500000  1.2  290.

The temperature field is used to calculate the local viscosity using the Sutherland law:

visc = visc_ref * (tf / Tref)^1.5 * (Tref + S) / (tf + S)

with tf being the local fluid temperature, visc_ref the dynamic viscosity at reference temperature Tref, and S the Sutherland temperature.

Restart, fix_modify, output, run start/stop

No information about this fix is written to binary restart files. No fix_modify option applies to this fix. This fix computes no output, which can be accessed by various output commands. No parameter of this fix can be used with the start/stop keywords of the run command.

Restrictions

none

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