# Discussion Forum

## how to define analytic function

 Topics: 4.3
RSS feed   |   Turn on email notifications   |   1 Reply   Last post: October 6, 2012 9:43pm UTC

Bin Xu

October 5, 2012 2:21pm UTC

how to define analytic function

Hi,

I am using Joule heating to simulate the voltage,current and temperature distribution.

I have 2 blocks whose size are both 2cm*2cm*1cm, I put them together to form a union(the big block size is 2cm*2cm*2cm).

I apply a voltage(U is a known value) to them in Z axis, it is supposed the voltage of upper half part is U1 and the voltage of lower half part is U2(U1+U2=U).

It is assumed the electrical conductivity of upper half part is equal to U1 and the electrical conductivity of lower half part is equal to 2*U2.

I would like to know how to set the variables and analytic function for material's electrical conductivity.

Thanks.

Ivar Kjelberg

October 6, 2012 9:43pm UTC in response to Bin Xu

Re: how to define analytic function

Hi

I'm not sure I catch you completey, but for your example, if you choose 2D JH physics and stationary solver

Then geoemtry, set to cm, and add a square of 2cm and add a 1 cm" layer" (default by on the bottom) you have your geometry without doing anything more

Then add a first material, by default it selects both domains, and asks for values for the relevant material parameters such as Conductivity in S/m (invese of resistivity in Ohm*m), the dieletric constant often 1 or close to, the heat conductance, k, density rho, and specific heat capacity. These can be values from the litterature, or curves (see examples from the build-in material DB) depending on the temperature T and or pressure pA ...

You need to set your BCs, as JH solves for V and for T you need at leas some Direchlet BC for both, such as bottom line( boundary) set to electric GND (0V) and top set to Terminal and 1V, and i.e. bottom boundary set to constant temperature 20[degC]

then you solve, and postprocess at will

--
Good luck
Ivar

Rules and guidelines