Additional boundary condition in heat conductivity problems with variables medium physical properties

The field of obtaining approximated analytical solutions of mathematical physics boundary problems is developed. It is based on additional boundary conditions, allowing to define any item number of model (approximated) analytical solutions and to obtain solutions with the required accuracy degree. Physical meaning of additional boundary conditions lies in implementation of the basic differential equation and its different order derivatives at boundary points of the field. It leads to implementation of differential equation within the given field with number of approximations dependant on the accuracy.