Card 9 - QNODE Heat Load Definition

This optional card defines heat loads for elements.

Parameters: KODE, N1, T1, T2, T3, T4, T5

KODE

KODE is the code QNODE (or 1)

N1

N1 is an element number, or a group name.

T1

T1 is the specified heat load, or heat load/area, or heat load/volume into N1.

T2

T2 may be:

  • the specified time when the heat load occurs (this option is not recommended). T2 may not be < 0, unless T2 = -99990.
  • the code CONSTANT (or -99990) for constant heat loads. If T2 is blank it defaults to CONSTANT.
  • the form Tn (e.g. T6), where n is a table number specified by TABTYPE and FIELDTYPE Cards, and table n specifies a heat load multiplier. The total heat load will then be equal to the value interpolated from table Tn, times T1, times the geometrical multiplying factor computed from T3.
  • the form En (e.g. E6), where n is an expression number specified by EXPRESSION card, and expression n specifies a heat load multiplier. The total heat load will then be equal to the value evaluated from expression En, times T1, times the geometrical multiplying factor computed from T3.

T3

T3 may be:

  • blank, ABSOLUTE, or 0. T1 is the heat load into element N1.
  • AREA (or 1E36). T1 is the heat load per unit area into element N1.
  • LENGTH (or 4E36). T1 is the heat load per unit length into element N1. This is applicable to beam elements only.
  • TOTAL (or 2E36). The heat load is redistributed among the elements of group N1 in proportion to their areas or volumes.
  • VOLUME (or 3E36). T1 is the heat load per unit volume into element N1. For planar and beam elements the volume is calculated by multiplying the length or area by the cross-sectional area or thickness.

For T3 = TOTAL heat load is computed as:

where:

  • AV(I) is either the volume (for solid elements) or area of element I (for shells and beams), or unity (for non-dimensional element), where I is a member of the N1 group. All the elements of group N1 must be of the same type, i.e. solid and non-solid elements may not be mixed.
  • Q(I) is the heat load to element I, which is a member of the group N1.
  • Ω(T2,I) is the interpolated variable where T2 is a table.

If T2 is a spatial table (field or EID dependent), then Q(I) is calculated with a weighting factor Ω(I) interpolated from this table:

When T2 includes a reference to an expression, either directly or through a table, then each spatial field, referenced in that expression is normalized by a factor that makes the area-weighted average of that field equal to one. The averaging is performed over the N1 element group.

If N1 is a single element, the heat load is applied to the element.

T4

T4 specifies the layer for multilayer elements. Non-homogeneous multilayer elements are specified on LAYER Cards, homogeneous multilayer elements are specified on PROP Cards.

  • 0, blank, or TOP, the element is not multilayer or heat load is applied to the top layer.
  • MIDDLE – heat load is applied to the middle layer.
  • BOTTOM – heat load is applied to the bottom layer.
  • ALL – heat load is applied to all the layers.
  • SPECIFY – heat load is applied to the T5th layer, as counted from the bottom layer. T4 = 1 is the same as T4 = BOTTOM.

T5

T5 is the layer number for T4 = SPECIFY.

Code example


QNODE 14 30 CONSTANT
$ HEAT LOAD OF 30 IS ADDED TO ELEMENT 14
QNODE 14 30 8 AREA  
$ A HEAT LOAD = 30*AREA(14) IS ADDED TO ELEMENT 14 AT TI

Notes

Orbital radiative heat loads calculated from geometry are automatically summed by the MEREL module with those specified on QNODE Cards.

A T2 parameter value other than CONSTANT or a table number is not recommended if orbital heat loads are also calculated. This is because it is necessary to match with T2 all the orbital time parameters on QNODE Cards, otherwise errors can result.

To work around this problem, it is recommended that you specify time-dependent heat loads on tables with INTERP, TABTYPE, and FIELDTYPE Cards, or with user-written subroutines. This will avoid the problem of matching all the time values if orbital heat loads are also calculated.