How to apply linearly varying pressure load on multiple plate elements?
If the gradient of the load aligns with one of the GCS axis, then you can use the Loads >> Static Loads >> Hydrostatic Pressure function to define linear pressure load over a number of plate elements.
If the load is to be applied with a gradient in a random direction, you can use the Loads >> Static Loads >> Plane Loads function, where you can define a nonuniform pressure load based on local coordinate system and then apply this to the plate elements in a given plane.