Card 6e - Thermal Coupling Request (CFD)

These options are used to couple convecting printed circuit board elements to adjacent fluid elements for the electronic systems cooling applications.

Parameters: L, N1S, N1F, N1D, N2S, N2D, HN1, KODE, EXP, P1, VX, VY, VZ

A number of special conditions apply:

The NEARC21-24 and NEARCB1-4 options define convective couplings between the board and the fluid. N1S should be the group name for the board, N2S should be the group name for the fluid. They create couplings between the board and the fluid equal to:

where:

  • A(N1)overlap is the area of the board element overlapping the area of the corresponding fluid element, less the area of all the components between the fluid and board elements.
  • h is the heat transfer coefficient calculated by TMG.
  • HN1 is a user-specified multiplier.
  • G is the conductance between the board and nearest fluid element.
  • N1F is the surface roughness value assigned to the circuit board for the NEARC21 - NEARC24 and NEARCB1-4 options only.
  • N1D defines the type of mesh correction to be applied to the convective couplings for the NEARC21 - NEARC24 and NEARCB1-4 options only.
  • N1D=0 no mesh correction.
  • N1D=1 forced convection mesh correction.
  • N1D=2 natural convection mesh correction.
  • N1D=3 automatic determination of mesh correction.
  • KODE may be NEARC21, NEARC22, NEARC23, or NEARC24.

L

L is the code AREA (or 11)

The NEARx (recommended) options connect the N1 elements to the nearest of the N2 elements.

KODE = NEARC21 or NEARCB1

NEARC21 (3921) or NEARCB1 (3931) calculate convective couplings with h(KODE, EXP) = 1 from the positive side of the board.

KODE = NEARC22 or NEARCB2

NEARC22 (or 3922) or NEARCB2 (3932) is similar to NEARC21, except that the couplings are from the negative side of the board.

KODE = NEARC23 or NEARCB3

NEARC23 (or 3923) or NEARCB3 (3933) is similar to NEARC21, except that h is computed by TMG.

KODE = NEARC24 or NEARCB4

NEARC24 (or 3924) or NEARCB4 (3934) is similar to NEARC22, except that h is computed by TMG.

KODE = NEARC41

NEARC41 (or 3941) specifies components for NEARC21 couplings on the positive side of the board.

KODE = NEARC42

NEARC42 (or 3942) specifies components for NEARC22 couplings on the negative side of the board.

KODE = NEARC43

NEARC43 (or 3943) specifies components for NEARC23 couplings on the positive side of the board.

KODE = NEARC44

NEARC44 (or 3944) specifies components for NEARC24 couplings on the negative side of the board.

Notes

The only difference between the NEARCBx and NEARC2x options is the method of calculating the overlap area. The code of the thermal coupling for both on the file MODLF CNF Card will be 3921-3924.

The NEARC41-44 options define the association between the components and the boards. N1S should be a group name for components; N2S should be the group name for the board they lie on.

The matching of the NEARC4x and NEARC2x components Cards is important. NEARC41 Cards will be associated only with NEARC21 Cards; NEARC42 Cards will be associated with NEARC22 Cards, etc.

The NEARC41-44 option creates couplings between the component and the fluid equal to:

where:

  • A(N1) is the area of the component.
  • h is the heat transfer coefficient calculated by TMG. The roughness value and mesh correction flag used to calculate h is the one specified for the corresponding board elements on the NEARC21 Card.
  • HN1 is a user-specified multiplier.
  • KODE may be NEARC41, NEARC42, NEARC43, or NEARC44.