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LabelEdgeHT Object

Properties

Methods

Summary

Physical properties of an edge for problems of steady-state and transient heat transfer.

Details

The LabelEdgeHT object represents physical data applicable to the edge label for heat transfer problems.

When you need to set or modify some physical parameters for the edge label, you have to get the LabelEdgeHT object using the Content property of the Label object, modify the LabelEdgeHT object using its properties, and then put it back in the Label object assigning your LabelEdgeHT to the Content property of your Label object.

The LabelEdgeHT object inherits methods and properties from its base class LabelEdge. Here the LabelEdge's properties take the following meaning:

Dirichlet as Double and DirichletLinear as LinFunc	Set and get the known value of the temperature T₀ at the edge. (The boundary condition of the first kind).
Neumann as Double	Sets and gets the normal component of the heat flux density F_n. (The boundary condition of the second kind).
Floating as Boolean	If True, defines the constant temperature boundary condition. The surface is assumed to have a constant but unknown temperature value T=const.

With heat transfer problems, an edge label can be defined as a Dirichlet (first kind) condition, or a constant temperature boundary condition, or one or more boundary conditions of following kinds:

flux (second kind) boundary condition;
convective boundary condition;
radiation boundary condition;

In addition to the generic properties of LabelEdge listed above, the LabelEdgeHT object provides methods for setting and reading those special kinds of boundary condition:

GetConvection (Alpha, T) as BOOL	Returns True if the convection boundary condition is set, otherwise returns False. In the method returning True, the optional parameters Alpha and T as double take the value of film coefficient and the temperature of contacting fluid medium respectively.
SetConvection (bSet, Alpha, T)	Sets or removes the convection boundary condition. The first parameter bSet as BOOL sets the boundary condition if it is True and removes otherwise. The Alpha parameter contains the value of film coefficient and T - the contacting medium temperature.
GetRadiation (Beta, T) as BOOL	Returns True if the radiation boundary condition is set, otherwise returns False. If the method returns True, the optional parameters Beta and T as double take the value of emissivity coefficient and the ambient radiation temperature respectively.
SetRadiation (bSet, Beta, T)	Sets or removes the radiation boundary condition. The first parameter bSet as BOOL sets the boundary condition if it is True and removes otherwise. The Beta parameter contains the value of emissivity coefficient and T - the ambient radiation temperature.
GetFlux (Flux) as BOOL	Returns True if the second kind boundary condition is set, otherwise returns False. If the method returns True, the optional parameter Flux as Double takes the value of the normal component of the heat flux.
SetFlux (bSet, Flux)	Sets or removes the second kind boundary condition. The first parameter bSet as BOOL sets the boundary condition if it is True and removes otherwise. The Flux parameter contains the normal component of the heat flux.

In the following example we create three new labels for the edges. For one of them called "T=const" we set the boundary condition to the first kind with temperature value 373. For the second edge "Convective", a convection boundary condition is defined, and for the third one - the radiation condition.

Dim lb As QuickField.Label
Dim lbCnt As QuickField.LabelEdgeHT

Set lb = prb.Labels(qfEdge).Add
lb.Name = "T=const"
Set lbCnt = lb.Content
lbCnt.Dirichlet = 373#
lb.Content = lbCnt

Set lb = prb.Labels(qfEdge).Add
lb.Name = "Convective"
Set lbCnt = lb.Content
lbCnt.SetConvection True, 0.0115, 95
lb.Content = lbCnt

Set lb = prb.Labels(qfEdge).Add
lb.Name = "Radiative"
Set lbCnt = lb.Content
lbCnt.SetRadiation True, 0.2, 500
lb.Content = lbCnt