Card 9 - FMHDEF - Free Molecular Heating Request

These FMHDEF cards define a free molecular heating (FMH) request.

ID

ID is the free molecular heating request number. ID is an integer value common to all associated FMHDEF Cards.

FMHDEF1

Field Value Description
FMHDEF1 FMHDEF1 or 68 mnemonic
ID integer ID number
SHADOPT FMHS1 Shadowing for some elements
FMHSALL Shadowing for all elements
TIME Real value Time value
CONSTANT Flag CONSTANT
Blank blank (SHADOPT=FMHSALL) defaults to CONSTANT
FRONTGRP mnemonic or integer Element ID or group name of front facing elements
REVGRP mnemonic or integer Element ID or group name of reverse facing elements

FMHDEF2

Field Value Description
FMHDEF2 FMHDEF2 or 69 mnemonic
ID integer ID number
HEATFLUXMODE FLUX The heat flux is entered by the user
VELOCITY_DENSITY The velocity and density are entered by the user
DENSITY The density is entered by the user while the velocity is calculated from orbit
ALTITUDE_DENSITY The density is altitude dependent. The altitude and the velocity are calculated from orbit.
FLUX Real value Value for constant flux
Table Table for time dependent flux
VELOCITY Real value Value for constant velocity
Table Table for time dependent velocity
DENSITY Real value Value for constant density
Table Table for time dependent density

FMHDEF3

Field Value Description
FMHDEF3 FMHDEF3 or 70 mnemonic
ID integer ID number
FMHACC Real value FMH accommodation factor
HEATFLUXDIR VECTOR Direction defined by vector VECX, VECY, VECZ or table TX, TY, TZ
ORBIT Direction obtained from orbit definition

Code example

$ ----------------------
$ Free Molecular Heating
$ ----------------------
$
MONTECARLO ON 2000 ABSOLUTE HTFRAD 0
FMHDEF1 1 FMHSALL CONSTANT
FMHDEF2 1 FLUX  1.000000E+02 NONE 0 NONE 0
FMHDEF3 1 1.000000E+00 VECTOR 1.0 1.0 1.0 T42 T43 T44
MONTECARLO OFF

Note

The incident flux qi generated by free molecular heating is 0.5 * ρ * V3.

Where:

  • ρ is the atmospheric density.
  • V is the spacecraft’s velocity.

The amount of heat absorbed, qa is equal to the incident flux multiplied by the accommodation coefficient, α, 0 ≤ α ≤ 1.

qa = α * qi