1. A method of selecting an operating parameter value for supplying energy to an ablation electrode, comprising: (a) receiving a first signal representing a value of a fluid flow rate; (b) receiving a second signal representing a value of an impedance; (c) receiving a third signal representing a value of a positive distance from an ablation electrode surface to a target tissue surface; and (d) selecting a value for an operating parameter for supplying energy to the ablation electrode as a function of the first, second and third signals; wherein: (d) comprises selecting the operating parameter value based on relationships established between (1) values of the operating parameter and (2) fluid flow rate values, impedance values and distance values; the relationships are established with analyses of a numerical model of transmission of energy to biological tissue by an ablation electrode; the numerical model comprises a finite element model; and to model a tissue temperature distribution, the numerical model comprises equations for modeling an electric field created by the ablation electrode, heat generated by the electric field, and a velocity field of the fluid flow.