| 摘 要： | The variational principle in terme of stream function (?) for free surface gravity flowis discussed by the formulation of first-order variation in a variable domain. Because ofdifferent transversal conditions adopted, there are four forms of variational principle interms of (?).An air-filled cavity flow with given discharge and total energy is then analysed by finiteelement method.At the end of the cavity, the free stream line is tangent to a short fictitiousplate of given length, which joins the fixed boundary at an angle to be determined.Thecondition that the free stream line should be tangent to the fixed boundary at the point ofseparation makes the solution unique.Finally curves giving the cavity length as a function of the Froude number,cavitypressure and channel bottom slope are presented.
|
