# CONV

Bulk Data Entry Defines a free convection boundary condition for heat transfer analysis through connection to a surface element (CHBDYE card).

It can also used to define the ambient points for free convection, or for convection with fluid flow via CAFLUID entry.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CONV EID PCONID   CNTRLND TA

## Definitions

Field Contents SI Unit Example
EID CHBDYE surface element identification number.

No default (Integer > 0)

PCONID Convection property identification number of a PCONV entry.

No default (Integer > 0)

CNTRLND Control node for time dependent convection coefficient.

Default = 0 (Integer > 0)

TAi TAi fields can be used to define one of the following:
• Ambient points used to specify ambient temperature for free convention; and/or,
• Specify points for convection with fluid flow belonging to CAFLUID elements. Depending on the location of the nodes belonging to the corresponding CHBDYE entry, the proximal nodes of the CAFLUID entry can be referenced on the CONV entry to define the appropriate setup for CAFLUID 1D fluid flow for heat transfer.

No default (Integer > 0)

1. The basic exchange relationship is expressed as: (1)
$q=\left(c*H\right)*\left(T-{T}_{Amb}\right)$
Where,
$H$
Free convection heat transfer coefficient specified on a MAT4 entry, referred by a PCONV entry
$c$
Time-dependent multiplier provided by SPCD, which constrains node identified by CNTRLND field
$T$
Grid temperature
${T}_{Amb}$
Ambient temperature
2. The time-dependent multiplier ( $c$ ) for the heat transfer convection coefficient is controlled via control nodes (CNTRLND field). The same nodes should be referenced on SPCD entries. Time-dependency is activated by referencing the corresponding SPCD entry on TLOAD1/TLOAD2 entries.
3. CONV is used with a CHBDYE entry having the same EID.
4. In linear steady-state heat transfer analysis, ambient temperature is specified by SPC of the TA point.
5. This card is represented as a secondary element in HyperMesh.