Heat propagation in waters - physical fundamentals

The physical fundamentals necessary to understand mathematical models of the environment are given. It was found that considerable mathematical and physical effforts are necessary to achieve sufficient accuracy in the calculation of temperature, flow rate, etc. The so-called eco- and transport models are less accurate than purely physical models, due to the fact that they are essentially a quantitative formulation of biological processes. With regard to the given numerical methods of solution, it is interesting to note that a partial differential equation is reduced here to a coupled system of normal first order differential equations. (orig.)