nodes_cc.m

用无网格法计算VAN DE POL 振子

function [m_i,v_i,EI,eps,ome,Amp,D_out,const1,const2,C_t,D_t,m_t] = nodes_CC(yi,time,zz,n)
% THIS M_file IS WRITTEN TO CALCULATE THE NODAL VALUES OF DAMPING, TOTAL UNIT MASS OF 
% RISER AND SOME CONSTENTS.
%
% Input/parameter description
%        - A,a parameter of fluid dynamics         
%        - A_in,inner section area of riser
%        - A_out,outer section area of riser
%        - C_s,damping of structre
%        - C_L,instantaneous lift coefficient
%        - C_L0,aplitude of lift coefficient when the cylinder in steady
%        flow
%        - C_m,added mass of fluid
%        - C_ad,added damping of fluid
%        - C_D,damping coefficient of fluid
%        - C_D0,aplitude of damping coefficient of fluid when the cylinder 
%        in steady flow
%        - C_t,total damping
%        - D_in,inner diameter of riser
%        - D_out,outer diameter of riser
%        - epsilon,a small coefficient of nonlinearity in ossilator model
%        - EI,bending stiffness
%        - K_s,stiffness of riser
%        - K_g,geometrical stiffness of riser
%        - K,total stiffness
%        - l,length of riser element
%        - L,length of riser
%        - L_w,water depth
%        - m_i,mass of inflow per length
%        - m_r,mass of riser per length
%        - m_ef,efficient mass of riser per length
%        - m_a,fluid added mass of riser per length
%        - m_t,total mass
%        - miu,poision ratio of riser
%        - omega_f,angular frequence of the incident flow pulsation
%        - P_top,pressure on thetop of riser
%        - phi_y*,general displacements of riser
%        - psi_q*,general "displacements" of lift
%        - q,coefficient of lift oscillator,and q=C_L/C_L0
%        - rho_w,density of ocean water
%        - rho_i,density of inflow
%        - rho_r,density of riser
%        - T_top,top pre-tension of riser
%        - T_ep,efficient top pre-tension of riser
%        - T_ef,efficient tension of riser
%        - T_w,H,omega_w,k:are period,height,frequence of wave and wave
%        number respectively
%        - U,total fluid velocity
%        - v_c,velocity of current
%        - v_i,velocity of inflow
%        - v_w,horizontal velocity of wave
%        - z,vertical coordinate of middle point of each element
%        - z_1,up node of element
%        - z_0,down node of element
%  Output 
%        - C,damping matrix/row victor 
%        - C_b,b=bar and this is danping matrix/row victor of ossilator
%
% LOAD GIVEN DATA
given_data; 
x = 0;

Amp = Amp; D_out = D_out;
A_in  = pi * D_in^2/4; 
A_out = pi*D_out^2/4;
m_i = rho_i*A_in;       
m_r = rho_r*(A_out-A_in);
m_a = 1/4*C_m*rho_w*pi*D_out^2;
v_c = v_c.* (zz/L);

zz1 = zz(zz >= (L-H/2));  zz2 = zz(zz < (L-H/2));
v_w = pi*H/T_w * exp(k*(-zz1+L.*ones(1,length(zz1)))) * cos(k*x+omega_w*time); 
U = v_c(1:length(zz1)).*ones(1,length(zz1)) + v_w; 
U(length(zz1)+1:n) = v_c(length(zz1)+1:n);
omega_f = 2*pi*St/D_out.*U;

eps = epsilon; ome = omega_f;
m_t = m_r + m_i + m_a;
const2 = (m_r+m_i-rho_w*A_out)*g;
const1 = (m_i*v_i.^2-T_top+A_in*P_top*(1-2*pr))*ones(1,n) - const2*(zz-L.*ones(1,n));
D_t = 1./4 * rho_w*D_out*C_L0.* U.^2;

C_ad = rho_w *D_out.*(C_D0.*U) / 2; 
C_t = C_s*ones(1,n) + C_ad;

return