Heat equation with Delta Dirac function as boundary condition

Sorry for being unclear. My Right hand side in this problem, is not associated with Delta Dirac Function. I’ll try to explain in a better way. I have the heat equation and what I’m trying to do is use different Dirichlet boundary conditions in this equation. Specifically, I’m trying to set the corners of the square with a heat source stated by me as this u_d expression in this domain, and in a circle of radius 0.25 centered at this square domain, an impulse represented by the Delta Dirac function. Basically, what I tried with this b, is based on the topic:

But I’m trying to change this of acting in a point to act on this circular subdomain. And, sorry, I have noticed now that my formulation is not correct, it is supposed to be a function f at the right hand side of Heat Equation:

image

The function f is actually:

f = Constant(beta - 2 - 2*alpha)