Laws of symmetry of dynamic processes in media with films

A sufficiently wide class of boundary value problems simulating dynamic processes of heat and mass transfer is considered in media with strongly or poorly permeable films. Formulas expressing the solutions to these problems with films via the solutions to the same problems without films are derived. Based on the general formulas, the following laws are obtained-if a strongly permeable film is introduced into the processes without films, the potentials at any two points symmetrical with respect to the film will change by the same value. Similarly, if a poorly permeable film is introduced into the processes without films, the potentials at the points symmetrical with respect to the film will change by the value of the same modulus and opposite sign. Expressions for potential increments caused by the presence of films are found. For the Poisson equation, similar laws are obtained with films in the form of a circle.