This book presents a new calculation method for heat transfer in coupled convective-conductive fluid-wall systems under periodical intensity oscillations in fluid flow. It is demonstrated that the true steady-state mean value of the heat transfer coefficient has to be multiplied by a newly defined coupling factor. For characteristic periodic heat transfer problems, analytical solutions are given for the coupling factor. To facilitate engineering application, the monograph also presents the analytical results in accompanying tables and diagrams. The information in this book will be useful to all engineers dealing with heat transfer.