Sophisticated numerical models that solve the coupled mass and energy transport equations for nonisothermal fluid flow in a porous medium have been successfully used to match analytical results as well as field data for aquifer thermal energy storage (ATES) systems.^Generally these models are expensive and time-consuming to use.^Typically an ATES study is concerned primarily with energy balances and heat flows.^Often the fluid flow field is simple and reaches steady-state rapidly.^As an alternative for this sort of ATES problem the Steady Flow Model (SFM), a simplified but fast numerical model, has been developed.^Rather than solving the mass transport equation to obtain a fluid flow field that varies with time, a steady purely radial flow field is prescribed in the aquifer, and incorporated into the heat transport equation which is then solved numerically.^While the radial flow assumption limits the range of ATES systems that can be studied using the SFM, it greatly simplifies use of this code.^The preparation of input is quite simple compared to that for a sophisticated coupled mass and energy model, and the cost of running the SFM is far cheaper as well.^Furthermore, the simple flow field allows use of a special calculational mesh that eliminates the numerical dispersion usually associated with the numerical solution of convection problems.^The present report defines the problem considered, briefly outlines the algorithm used to solve it, then describes the input and output for the SFM.