How do you set up a subdomain for a source that grows in size?
Subdomains do not normally change size but it is possible to set a subdomain to be the whole domain and use a CEL expression to define the source volume. For example the following partial CEL computes a volume inside a cylinder of radius 0.3m and height 0.3m. The CEL variable insideSource will be 1 inside the source region and zero outside it. It is a simple matter to modify this expression to be a function of time. LIBRARY: CEL: EXPRESSIONS: z0 = 0.0 [m] x0 = 0.5 [m] y0 = 0.5 [m] sourceRadius = 0.3 [m] sourceHeight = 0.3 [m] unitL = 1 [m] rSource = sqrt((xx0)^2 + (yy0)^2) hSource = zz0 insideSource = step((sourceRadiusrSource)/unitL)*step((sourceHeighthSource)unitL) source = insideSource * 100 [W m^3] END END END >update FLOW: DOMAIN: Domain 1 SUBDOMAIN: Subdomain 1 SOURCES: EQUATION SOURCE: energy Option = Source Source = source END END END END END >update It is also possible to compute the actual volume of the source region. This may be important if a total source is required and/or the source volume includes non fluid regions such as cut outsolids. Note that you cannot use the 'Total Source' option in CFXPre because that will divide the source value by the volume of the subdomain which is now the whole domain. Instead, a variable can be defined to be equal to the insideSource variable and a CEL expression can be used to compute the volume integral of this variable. It is a good idea to set an appropriate minimum volume to prevent a division by zero error: LIBRARY: ADDITIONAL VARIABLE: SourceFlag Option = Definition Tensor Type = SCALAR Units = [ ] Variable Type = Unspecified END CEL: EXPRESSIONS: volSource = volumeInt(SourceFlag)@Subdomain 1 minVolume = 0.001 [m^3] source = insideSource * 100[W] / max(volSource, minVolume) END END END FLOW: DOMAIN: Domain 1 FLUID MODELS: ADDITIONAL VARIABLE: SourceFlag Additional Variable Value = insideSource Option = Algebraic Equation END END END END >update 

