Finite element solution to transient asymmetric heat conduction in multilayer annulus Research
This study investigate the heat transfer and thermal stresses for the time-dependent asymmetric heat conduction in a multilayer annulus by using finite element method. The realistic problem of isotropic multilayer annulus subjected to heat flux with internal heat generation and initial temperature is solved. The results of temperature and thermal stress have been computed numerically, illustrated graphically and interpreted technically. These results may be used in many engineering problem like combustion chamber, electric generator, compressor, hydraulic pumps etc. MSC: 35G30 • 35K20 • 74S05 • 80A20 • 80M10
Finite integral transform method to solve asymmetric heat conduction in a multilayer annulus with time-dependent boundary conditions
Abstract The separation of variables ( SOV ) method has recently been applied to solve time-dependent heat conduction problem in a multilayer annulus. It is observed that the transverse (radial) eigenvalues for the solution in polar ( r - θ ) coordinate system are always real numbers (unlike in the case of similar multidimensional Cartesian problems where they may be imaginary ) allowing one to obtain the solution analytically. However, the SOV method cannot be applied when the boundary conditions and/or the source terms are time-dependent, for example, in a nuclear fuel rod subjected to time-dependent boundaries or heat sources. In this paper, we present an alternative approach using the finite integral transform method to solve the asymmetric heat conduction problem in a multilayer annulus with time-dependent boundary conditions and/or heat sources. An eigenfunction expansion approach satisfying periodic boundary condition in the angular direction is used. After integral transformation and subsequent weighted summation over the radial layers, partial derivative with respect to r -variable is eliminated and, first order ordinary differential equations ( ODEs ) are formed for the transformed temperatures. Solutions of ODEs are then inverted to obtain the temperature distribution in each layer. Since the proposed solution requires the same eigenfunctions as those in the similar problem with time-independent sources and/or boundary conditions—a problem solved using the SOV method—it is also “free” from imaginary eigenvalues.
A new analytical method to solve the heat equation for a multi-dimensional composite slab
A novel analytical approach has been developed for heat conduction in a multi-dimensional composite slab subject to time-dependent boundary changes of the first kind. Boundary temperatures are represented as Fourier series. Taking advantage of the periodic properties of boundary changes, the analytical solution is obtained and expressed explicitly. Nearly all the published works necessitate searching for associated eigenvalues in solving such a problem even for a one-dimensional composite slab. In this paper, the proposed method involves no iterative computation such as numerically searching for eigenvalues and no residue evaluation. The adopted method is simple which represents an extension of the novel analytical approach derived for the one-dimensional composite slab. Moreover, the method of 'separation of variables' employed in this paper is new. The mathematical formula for solutions is concise and straightforward. The physical parameters are clearly shown in the formula. Further comparison with numerical calculations is presented.