Convection to Environment types

Convection to Environment type

The Convection to Environment type is an efficient way to model convection when certain convection values are previously determined, either experimentally or by reference to other analyses. Use the Convection to Environment type of the Convection to Environment constraint when values for convection magnitude are known. The type of known convection magnitude data available to you determines the option you select and the solver behavior.

• When the known data includes a convection coefficient, h, that is constant, time dependent, or temperature dependent, select the Convection Coefficient option. The convection coefficient can also vary spatially in addition to time or temperature. For a temperature dependent convection coefficient, the thermal solver uses the average temperature between the primary selection element temperature and the environment temperature to interpolate the convection coefficient.

• When the known data includes a constant convection parameter and exponent, specify the Parameter and Exponent option. The solver computes the convection coefficient as follows: h = c × ΔTexp. When there is a temperature gradient in the selected elements, the thermal solver computes the convection coefficient for each element locally, which results in varying convection coefficient on the various element.

In both cases, the solver models heat convection as qc = h As(Ts - Te).

Note:

If you specify a spatially-varying temperature in the Environment group, you must specify the same temperature units for model units and solution units.

You can specify from which side the thin shell or multi-layer shell elements convect: top, bottom, or both top and bottom. When you specify top and bottom, you can define different magnitude types and values for both sides.

Free Convection to Environment type

The Free Convection to Environment type models natural convection from geometry you select using standard correlations for free convection from specific geometry.

With the Free Convection to Environment type:

• You must select the appropriate correlation based on selected surface geometry.

• The software calculates a single global heat transfer coefficient for the entire convecting surface.

• The convecting surface is always assumed to be smooth.

• To establish the fluid environment, you define the fluid temperature and the material properties of the environmental fluid.

Buoyancy forces arising from density changes in the fluid due to heating are accurately modeled. However, the correlations used for the Free Convection to Environment constraint type assume a still fluid condition; inaccuracies may result if "chimney" effects predominate. Under these conditions use 3D flow convection modeling techniques.

An alternative method for modeling free convection to environment is to use the Forced Convection to Environment constraint type instead. This provides a more accurate correlation at higher velocities. You can manually calculate velocity due to buoyancy and use the value to approximate this flow condition.

Forced Convection to Environment type

The Forced Convection to Environment type models forced convection from geometry you select. It uses standard correlations for forced convection from specific geometry oriented to the stream. The software calculates a single global heat transfer coefficient for the entire convecting surface. You must select the appropriate correlation, and define the fluid velocity and temperature. The convecting surface is always assumed to be smooth.

You can define the material properties of the environmental fluid by selecting either the predefined materials Air or Water, or by defining any material with fluid properties.

How do I

Create a Convection to Environment constraint

Learn more

Convection to Environment

Free convection correlations

Forced convection correlations

Inputs to expressions

Look up more details

Auto-generated 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

Convection to Environment types, 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 } });