vary velocity along the wall

[hanybit]

Hello all,
I need your help to write a velocity function to vary the velocity magnitude along the wall instead of having it of the same magnitude? I tried many times but always got an error, any ideas on how to implement it?

I used to implement it in underworld in this way
velFunc = -Model.y / GEO.nd(Model.maxCoord[1]) * GEO.nd(vmax-vmin) + GEO.nd(vmax)
where
vmax=1.5 cm/yr
vmin=0.15 cm/yr

in ASPECT I have the same velocity along the boundary?

subsection Function
set Coordinate system = cartesian
set Variable names = x,y,z,t

# 0 deg obliquity, 10 mm full extension rate
#set Function constants  = mm=0.001, yr=1, vx_full=10.000 , vy_full=0.0000, DZ=200e3, DX=450e3  

any ideas??

[gassmoeller]

Hi @hanybit,
this should absolutely be possible with the function syntax. Take a look at this example cookbook, which implements both a variable velocity (a step function with variable transition position), and a smooth variable initial temperature using function plugins. This page also describes the syntax in more details.
Let us know if you have any remaining questions or if something on the pages is unclear.