[Chesterton]

For various reasons, i'd like to create a visualisation of the pressure in my model compared to the static pressure at any point for its corresponding free surface level.

So, what I'd like to do is write an expression something like:

Pressure difference = Static Pressure - Modelled Pressure

Where:

Static Pressure = FreeSurfaceElevation - Z coordinate at that point
Modelled Pressure = Modelled Pressure in m of head

I've struggled for some reason - any ideas? I'd settle for simply being able to use the z coordinate in the equation and assume a static water level if that's possible.

[JBurnham]

You should be able to do this with the Calculator feature in FlowSight (comes with v11). First you have to have the free surface elevation added to the output: before you run, turn on Model Setup > Output > Additional output > Hydraulic data.

In FlowSight:
Load the output file.
Click on the Calculator icon in the upper left corner.
Switch to the "Build your own functions" tab
Give the variable a name
Enter the desired expression using the variables from the list and the keypad on the dialog
Select all of the mesh blocks to define the "selected parts".
Choose "Evaluate for selected parts".

When you define the variables, define each variable sequentially using the previously calculated variables. FlowSight doesn't like doing certain commands at the same time as others. For example, define the z-coordinate (zc), then define the static pressure (ps) using the calculated z-coordinate, then the modeled pressure (pm), and finally the pressure difference (dp).

When you go to create the variable, select all of your mesh blocks as the parts to be used for the evaluation.