When creating a User Surface in ANSYS CFD-Post using the option from contour or an Iso Clip object to limit geometrically a wall boundary, it will be not possible to plot the variable Heat Flux on them. The reason is that Heat Flux is a boundary only variable and it can not be interpolated on the User Surface or the Iso Clip. One possibility to get the Heat Flux on a wall patch is to create the patch at mesh level. Another way in ANSYS CFD-Post will be to create: 1. a ‘mask’ variable using step functions or if statements. It should have a 1 where the user surface is and zero elsewhere. For example, if geometry should be limited in x-direction, so that only positive x-coordinates are from interest, the expression will look like: mask = step(X*1 [m^-1]-0) 2. a new MyHeat Flux variable, that equal to Heat Flux times the mask: myHeatFlux = Heat Flux*mask Plots and expression evaluations at the corresponding boundary condition are now possible with the User Variable MyHeatFlux. Please find an example attached.<\/p>\n