Abstract: This paper points out that if the line of water surface in a prototype river is similar to that in a model river, both prototype river and model river will satisfy the gravity similarity criterion and the resistance similarity criterion. These two criteria must be satisfied in fixed bed river models. #br# According to the Beronoulli equation we shall obtrain the result shown above, but there will be a process before we can obtain it. #br# The following is the scale relations for the fixed bed river models: #br# (1) For the geometrically similar systems: #br#δn=δl^(1/6) or δλ=1 #br# (2) For the so-called distorted river models (here δl ≠δh): δn=（1/δl)^(1/2)(Rp/Rm)^(2/3) or #br# δλ=(1/δl)(Rp/Rm) #br# All these various formulae are based on the Bornoulli equation.

摘要： <正>一、问题的提出 河工模型比其他水力模型复杂,这是因为河道水流的运动是受重力作用及阻力作用两种作用的结果。重力作用是众所周知的;而决定阻力的要素是河道的床面条件,它包括床面的粗糙度,泥沙的粒径及组成,河床的几何形态等。现今在试验场要模拟这些条件,使模型河床的床面条件与原型河床的床面条件都相似是极难办到的。 在河工模型试验中,通常是采用使模型河道的水面线与原型河道的水面线相一致的办法。?

关键词: 河工模型, 河道水流, 水面线, 床面, 水力模型, 过水断面, 水流运动, 几何形态, 比尺, 粗糙度