# GenCase problem when dp > 2.0

Hi!

I have set up my 2D simulation such that I can scale everything using a variable. Right now there's fluid drawn using <drawbox> (the red box), and a complex boundary drawn using <drawextrude> (blue). Problem is, whenever I increase dp > 2, the boundary mostly disappears, leaving behind only individual points. Under, left, dp = 2, and right, dp = 2.01 . The shape mode doesn't seem to matter. Why is this and how could I remedy the situation?

The relevant XML is, I think, below. The whole XML is attached here:

<geometry>

<predefinition>

<newvar mapw="875" maph="798" />

<newvar simscale="2.0" />

<newvar simw="#simscale*mapw" simh="#simscale*maph" />

</predefinition>

<definition dp="#simscale">

<pointmin x="-0.2" y="1" z="-0.2" />

<pointmax x="#simw+simscale" y="1" z="#simh+simscale" />

</definition>

<commands>

<mainlist>

<setshapemode>dp | bound</setshapemode>

<setdrawmode mode="full" />

<setmkfluid mk="0" />

<drawbox>

<boxfill>solid</boxfill>

<point x="#simw*0.50" y="0" z="#simh*0.5" />

<size x="#simw*0.2" y="2.0" z="#simh*0.25" />

</drawbox>

<scale x="#simscale" y="1" z="#simscale"/>

<drawextrude closed="true">

<point x="510.1" y="0" z="759.4" />

<point x="510.7" y="0" z="758.8" />

<point x="510.6" y="0" z="760.7" />

...

## Comments

Remember when using DualSPHysics gencase, you are discretizing by applying a large "particle grid stencil", i.e. it draws the full volume of particles, and then starts removing unnecessary ones. This is atleast my understanding.

At some specific values this would then occure, but have you tried using dp = 4.0, dp = 2.5 etc. and seen what happens?

Kind regards

The resolution (dp) is not enough to represent such small structures. The size in Y is 2 (extrude y=2) is not enough for dp=2

Best regards

Thank you for your replies! Increasing the extrude value fixed this problem (I set it to extrude y=1000 now).

I saw this problem happening for every dp > 2.0, to varying degrees. But this is probably because I was extruding by exactly 2.

Best regards