1! 2! CalculiX - A 3-dimensional finite element program 3! Copyright (C) 1998-2021 Guido Dhondt 4! 5! This program is free software; you can redistribute it and/or 6! modify it under the terms of the GNU General Public License as 7! published by the Free Software Foundation(version 2); 8! 9! 10! This program is distributed in the hope that it will be useful, 11! but WITHOUT ANY WARRANTY; without even the implied warranty of 12! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13! GNU General Public License for more details. 14! 15! You should have received a copy of the GNU General Public License 16! along with this program; if not, write to the Free Software 17! Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 18! 19 subroutine hcrit(xflow,rho,b,theta,dg,sqrts0,hk) 20! 21! determine the critical depth 22! 23 implicit none 24! 25 real*8 xflow,rho,b,dg,sqrts0,hk,theta,tth,c1,xflow2, 26 & A,dBBdh,dAdh,BB,dhk 27! 28 hk=((xflow/(rho*b))**2/(dg*sqrts0))**(1.d0/3.d0) 29! 30 if(dabs(theta).lt.1.d-10) return 31! 32! critical depth for trapezoid, non-rectangular cross section 33! 34 tth=dtan(theta) 35 c1=rho*rho*dg*sqrts0 36 xflow2=xflow*xflow 37! 38 do 39 A=hk*(b+hk*tth) 40 dBBdh=2.d0*tth 41 dAdh=b+hk*dBBdh 42 BB=dAdh 43 dhk=(xflow2*BB-c1*A**3)/(xflow2*dBBdh-3.d0*c1*A*A*dAdh) 44 if(dabs(dhk)/dhk.lt.1.d-3) exit 45 hk=hk-dhk 46 enddo 47! 48 return 49 end 50 51 52