Evaluate a ball launched at multiple angles? Theta0 needs to be 30, 45, 60. I want to plot all 3 trajectories on the same plot

Question

aquiano 2016-9-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/303946-evaluate-a-ball-launched-at-multiple-angles-theta0-needs-to-be-30-45-60-i-want-to-plot-all-3-tra

评论： dpb 2016-9-21

%                       ***** PROGRAM 1.4 *****                            
% MOTION AND TRAJECTORY OF A SPHERICAL PROJECTILE IN A FLUID
% Reference: Computational Fluid Mechanics by Example (Biringen and Chow; Wiley 2011)
clc;
clear all;
format short e;
global A B C D NU PI
% ***** ASSIGN INPUT DATA AND START THE OUTPUT ON A NEW PAGE *****
 RHO = 8000.0;
 RHOF = 1.22;
 G = 9.8;
 DT = 0.1;
 TMAX = 10;
 IFRPRT = 5;
 T0 = 0.0;
 X0 = 0.0;
 Y0 = 0.0;
 W0 = 50.0;
  RHOBAR = RHOF/RHO;
  NU = 1.49E-5;
  PI = 3.14159; 
% PI = pi;
D = 0.05;
A = 1. + RHOBAR/2.;
B = (1. - RHOBAR)*G;
C = 3.*RHOBAR/(4.*D);
% ***** PRINTING HEADINS AND ASSIGN INITIAL CONDITIONS FOR EACH OF THE 3
% CASES WITH THETA0 = 30, 45 AND 60 DEGREES, RESPECTIVELY. THEN PRINT THE
% INITIAL VALUES *****
      THETA0 = 15.0;
      J=1
      THETA0 = THETA0 + 15.0;
      I = 1;
      T(I) = T0;
      X(I) = X0;
      Y(I) = Y0;
      U(I) = W0 * cos(THETA0*PI/180.);
      V(I) = W0 * sin(THETA0*PI/180.);
% ***** FOURTH-ORDER RUNGE-KUTTA METHOD IS USED TO INTEGRATE THE EQUATIONS
% OF MOTION, STOP THE COMPUTATION FOR ONE CASE IF THE PROJECTILE DROPS BACK
% TO ITS INITIAL LEVEL OR BELOW, PRINT DATA WHEN THE LAST TIME STEP IS
% REACHED OR WHEN THE COUNT I IS AN INTEGRAL MULTIPLE OF IFRPRT *****
      while (Y(I) >= 0.)
          [TSOL,SOL] = ode45(@FXY, [T(I), T(I)+DT], [X(I), U(I), Y(I), V(I)]);
          I = I + 1;
          T(I)=TSOL(end);
          X(I)=SOL(end,1);
          U(I)=SOL(end,2);
          Y(I)=SOL(end,3);
          V(I)=SOL(end,4);
          if (rem(I-1,IFRPRT) == 0)
              disp([T(I) X(I) Y(I) U(I) V(I)]);
          end
      end
      disp([T(I) X(I) Y(I) U(I) V(I)]);
      clear plot
      plot(X,Y)
      xlabel('X (m)'),ylabel('Y (m)')
      title('Trajectory of a steel sphere in air, initial velocity 50 m/s; initial projectile elevation 30 degrees')