A heated sphere of radius R is suspended in a large, motionless, body of fluid. It is desired to study the heat conduction in the fluid surrounding the sphere in the absence of convection.

Set up the differential equation describing the temperature T in the surrounding fluid as a function of r, the distance from the center of the sphere. the thermal conductivity k of the fluid is considered constant.

Integrate the differential equation and use these boundary conditions to determine the integration constants: at r = R, T = T_R; and at r = , T = T