Hello all,

I am running a simple convection model in a cartesian geometry where I need to calculate the T_melting in function of the hydrostatic pressure.

This hydrostatic pressure is depth dependent. I checked some puglins where there is a parameter called “in.pressure [i]” but, the manual says that this is the dynamic and hydrostatic pressure of the model.

So, I would need just to know the depth I guess “in.position[i]” of a point.

It could be computed like this:

hydrostaticpressure [i] = rho * gravity * in.position [i][1]

but I am not really sure how to extract that depth. Please, could you help me with this?

Thank you so much in advance.

cheers,

Kate:

the depth is something that can be computed from a position by the geometry model. This piece of code should do:

```
const double depth = this->get_geometry_model().depth(in.position[i]);
```

This command will show you a few places where this is already done:

```
grep -r 'depth(in.position' source/
```

Best

W.

Hi Katherine,

To add to Wolfgang’s message…

(1) The correct expression for hydrostatic pressure is the integral of `rho(z) g(z) dz`

, not `rho g z`

. The depth dependence of the density and gravity are important.

(2) Is there a reason you want to calculate the hydrostatic pressure? This isn’t a state property - rocks don’t “see” hydrostatic pressure, they see the true pressure (or more precisely, they see the Cauchy stress).

Because of the way ASPECT is designed, it is easier to calculate and use the full pressure than the hydrostatic pressure.

Best wishes,

Bob