fluent

%% 清理并定义初始变量
close all;
clc;
V_i=20;
a = 1 ; %半径
c =-a*2;
b =a*2;
n =a*50; %间隔
[x,y]=meshgrid([c:(b-c)/n:b],[c:(b-c)/n:b]');
%% 使圆柱内无流线
for i=1:length(x);
   for k=1:length(x);
      if sqrt(x(i,k).^2+y(i,k).^2)<a;
         x(i,k)=0;
         y(i,k)=0;
      end
   end
end
%% 定义极性变量
rho=sqrt(x.^2+y.^2);
theta=atan2(y,x);
%% 创建流函数和势函数
z=V_i.*sin(theta).*rho.*(1-(a^2./(rho.^2)));
w=V_i.*cos(theta).*rho.*(1+(a^2./(rho.^2)));
%% 绘制流网图
[u,v]=gradient(w);
max(abs(curl(x,y,u,v)),[],'all');
figure;
hold on;
shading interp;
d =2.5;dd = 5;%d用来调整箭头的间距，dd用来调整箭头长短
quiver(x(1:d:end,1:d:end),y(1:d:end,1:d:end),u(1:d:end,1:d:end)'./dd,v(1:d:end,1:d:end)'./dd,'color','r');%画箭头
n=100;
r=ones(1,n+1)*a;
t=[0:2*pi/n:2*pi];
contour(x,y,z,25,'-g','LineWidth',1);
hold on ;
contour(x,y,w,25,'-b','LineWidth',1);
hold on;
polar(t,r,'-k');
axis square;
title('圆柱体绕流');
grid off