Abstract: The dissimilar resistance of river diversion and closure models will lead to a large deviation between test results and actual situation. Factors affecting the similar resistance along the wall of long diversion tunnel are analyzed by using theoretical analysis and hydraulic calculation methods. The resistance crisis in the closure model test is revealed,and the approaches of solving the problem of resistance dissimilarity is proposed. In the case of tunnel diversion model,the modeling discharge capacity can be corrected by increasing the flow rate or fitting the relationship between the resistance coefficient and the model Reynolds number through system test because the water flow in tunnel diversion model is often in turbulence transition zone as restricted by the model scale,and the resistance coefficient of tunnel wall is a function of the model Reynolds number. In the case of closure model,the model water flow can be adjusted entering the self-simulation area by reasonably selecting the model scale to avoid resistance crisis because the similarity of thrust resistance coefficient must be satisfied when the blocks are similar in anti-shock stability,and the surrounding flow resistance coefficient is constant only when the model Reynolds number is 3×10⁴～2×10⁵.

Key words: river diversion and closure model, long tunnel diversion, similar turbulent resistance, similar thrust resistance coefficient, Reynolds number