Discussion Forum

Hello,
I am using Comsol 4.3b. I arrived in a problem. Could you please help me. The problem is, I have a system of reaction diffusion equation with no flux boundary condition, in which one of dependent variable has integral term with limit [-r,r]. In the Comsol documentation I read that, this can be done using integration coupling variable. In the settings window I put the expression of the integrand in the integration operator, but I do not see where I can specify the limit of integration. The system of reaction diffusion equations looks like (using latex),
$\frac{\partial R}{\partial t} = d \nabla^2 R + \nabla .(R\textbf{K}(R))$,
where $\textbf{K}(R) = a(M-b) \int_{-r}^{r}{\sigma (R) (M-g)}ds$ s a vector,where R, M are dependent variables, a, b, g, d are parameters, s is spatial increment, and $\sigma (R)$ is the logistic equation, has the form,
$\sigma (R) = h R max(1-\frac{1}{h} \int_{0}^{\infty} \int_{0}^{\infty} R dT_1 dT_2 , 0)$, h is a parameter, T_1, T_2 are independent variables.
I choose coefficient form of PDE (time dependent) with 2D.
Thanking you.
Best regards.
- Paramita Chatterjee