Two mathematical models, Tar Sand Reservoir Simulator 1 (TSRS1) and Tar Sand Reservoir Simulator 2 (TSRS2), are used to numerically simulate the thermal recovery of oil from tar sand in tube reactor tests conducted at Western Research Institute. The results from these two models are compared to the results from four Tar Sand Triangle tube reactor forward combustion experiments (Romanowski and Thomas 1986). Although the comparative analyses of the numerical simulations and the experimental results were hampered by the bypassing of air, reactor plugging, and the use of wall heaters during the experiments, the simulators predicted tube reactor performance reasonably well. The comparison of results indicates that air bypassing influenced measured oil yields, combustion temperatures, and reactor pressures and was most noticeable during the highest flux experiment. Non-adiabatic conditions resulting from the reactor wall heaters affected measured front velocities and combustion temperatures, and were most apparent during the lower flux experiments. The results from TSRS2 (which accounts for the steam-char, the CO/sub 2/-char, and the water-gas shift reactions) more accurately describe the forward combustion process. Accounting for these reactions results in lower combustion temperatures, higher combustion front velocities, and improved product gas compositions compared to the results from the TSRS1 simulations. 18 refs., 4 figs., 11 tabs.