Dear all, I have difficulty in solving this problem (see the figure in attached thumbnails) I have a rectangular shape with length/height of L and the thickness/width of [tex]\delta[/tex] Within the rectangular area, a heat conduction occurred. I would like to determine the temperature profile within the rectangular. Based on the right hand side figure, I take a small cell with size of dx times dy. Applying the energy balance within the cell. I have attached all the equation that I can think of, and also the boundary conditions. I have difficulty in solving the differential equation. Thanks in advance. note: [tex]\lambda[/tex] is thermal conductivity [tex]\alpha[/tex] is heat transfer coefficient, it is suppose to be dependent on x-location and time. I am going to simulate the heat transfer coefficient as a periodic function.