Free convection correlations

This page lists the available free convection correlations that the thermal solver supports. You specify these correlations in:

• The Free Convection to Environment type of the Convection to Environment constraint. You provide the fluid material.

• The Free Convection Coupling type of the Thermal Coupling - Convection simulation object. The fluid material is provided by the 1D fluid network.

• The HTCFREE function in expressions when you define Thermal Convecting Zone, Thermal Stream, or Thermal Void loads. You provide the plate convection side: TOP, BOTTOM, or BOTH.

Inclined plate correlation

The inclined plate correlation models natural convection from any non-horizontal plate. Depending on your choice from the Characteristic Information list, the thermal solver computes the convective heat transfer differently.

• Calculate from Element Set uses the selected convecting region to compute the convective heat transfer.

• Specify uses the specified characteristic length (1) and normal vector (2) to compute the convective heat transfer. The characteristic length should be the length of the plate along the direction of the flow.

To specify the inclined plate correlation in the HTCFREE function, enter INCLINED for the coupling type. If you do not provide the characteristic length value, the thermal solver computes the characteristic length as the length of the line formed when the gravity vector is projected onto the plate.

Horizontal plate correlation

The horizontal plate correlation models natural convection from any horizontal plate. Depending on your choice from the Characteristic Information list, the thermal solver computes the convective heat transfer differently.

• Calculate from Element Set uses the selected convecting region to compute the convective heat transfer.

• Rectangular uses the standard correlation for a horizontal rectangular plate of specified length and width.

• Circular uses the standard correlation for a horizontal circular plate of specified diameter.

• Arbitrary Shape uses the standard correlation for a horizontal plate of specified area and perimeter.

To specify the horizontal plate correlation in the HTCFREE function, enter HORIZONTAL for the coupling type. If you do not provide the characteristic length value, the thermal solver computes the characteristic length as the plate area divided by the specified perimeter. You specify the perimeter value, p, in the optional arguments as follows: 0,p.

Sphere correlation

The sphere correlation models natural convection on the outside of a sphere of the specified diameter.

This correlation is not supported in the HTCFREE function.

Cylinder correlation

The cylinder correlation models natural convection on the outside of a cylinder of the specified diameter, length, and axis orientation with respect to gravity.

This correlation is not supported in the HTCFREE function.

Parallel plate channel correlation

The parallel plate channel correlation models natural convection where an open channel is inclined to gravity. The thermal solver models convection of heat between the bottom plate and the top plate, and the natural convection resulting from air passing through the channel. The side (vertical) surfaces are assumed to be adiabatic. The plates are assumed to be relatively close compared to their size. You define the length of the channel along the direction of flow, the spacing between the convecting plates, and a vector normal to the plates.

This correlation is not supported in the HTCFREE function.

How do I

Create a Convection to Environment constraint

Learn more

Convection to Environment

Convection to Environment types

Forced convection correlations

Inputs to expressions

Thermal Coupling — Convection

Thermal Coupling — Convection types

Across gap coupling convection correlations

Look up more details

Auto-generated expressions

Thermal-flow functions in expressions

Quick links

Simcenter 3D Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal boundary conditions

Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Free convection correlations, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });