### Print value of velocity profile

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Dear FEniCS community,

I am working on free convective flow at vertical plate. The flow considered along the vertical plate which is taken along the x-axis and y-axis(horizontal) is normal to it.

I have problem in printing the value of velocity profile after plotting the result. How can I get the value of velocity if y=0.01?

Thank you for your help.

I am working on free convective flow at vertical plate. The flow considered along the vertical plate which is taken along the x-axis and y-axis(horizontal) is normal to it.

I have problem in printing the value of velocity profile after plotting the result. How can I get the value of velocity if y=0.01?

Thank you for your help.

Community: FEniCS Project

### 1 Answer

2

If your velocity is a dolfin function, which it should be, you can pass a point as an argument to your solution to get the solution value at the respective point:

```
from fenics import *
mesh = UnitSquareMesh(32,32)
fe = FiniteElement('Lagrange', mesh.ufl_cell(), 1)
V = FunctionSpace(mesh, fe)
u = interpolate(Expression("pow((x[1]-0.5),2)", element = fe), V)
P = Point(0.5, 0.1)
print u(P)
```

Does it mean P = Point(x,y)?

written
7 months ago by
raihan asimoni

hi klunkean , i am also facing a similar issue. Why have you used pow((x[1]-0.5),2 here ?.

I want plot the value of my output (voltage) at a particular point. Should i use the same approach ?

I want plot the value of my output (voltage) at a particular point. Should i use the same approach ?

written
6 months ago by
Ovais

1

I just used the function $u\left(x,y\right)=\left(y-0.5\right)^2$

`u`(`x`,`y`)=(`y`−0.5)^{2}as an example for the function evaluation. If your voltage is a dolfin function you should be able to evaluate it by calling it with a point as argument.
written
6 months ago by
klunkean

thanks. I ll try this.

written
6 months ago by
Ovais

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