i wrote this code for a particle moving with fluid toward a big sphere and depend on the reynold number of the fluid and diameter of the particle it will hit the big sphere or get over it with the fluid.this code is running but may be i have not def

%-- 18-04-2013 15:01 --%

x(1)=-4;

y(1)=1;

R(1)=sqrt(x(1)^2+y(1)^2);

p=1780;

f=1.2;

dp=100e-6;

m = 15.11e-4;

u(1)=1e-3;

v(1)=1e-3;

Ux(1)=(-1)*(1-1/(R(1))^3+3*y(1)^2/(2*(R(1))^5));

Uy(1)=3*x(1)*y(1)/(2*R(1)^5);

c=p*dp/f;

i=2;

RX(i-1)=u(i-1)*dp/m;

RY(i-1)=v(i-1)*dp/m;

ts=p*dp^2/(18*m);

cdu(1)=24/RX(1);

cdv(1)=24/RY(1);

check=5;

while check>0;

h1=(1/(cdu(i-1)*RX(i-1)))*(c)*(-1.33);

h2=(1/(cdu(i-1)*RX(i-1)))*c*(-1.33);

h3=(1/(cdu(i-1)*RX(i-1)))*c*(-1.33);

h4=(1/(cdu(i-1)*RX(i-1)))*c*(-1.33);

j=ts/10;

x(i-1)=j/3*(h1+(4*h2)+(2*h3)+h4);

x(i-1) = zeros(50,50); %initialize as x(1)

y = zeros(50,50); %initialize as y(1)

if(RX(i-1) >= 3.0)

cdu(i-1)=(24/RX(i-1))+(4/RX(i-1)^(1/3));

elseif(RX(i-1) >= 0.5)

cdu(i-1)=(24/RX(i-1))+(3.6/RX(i-1)^(0.313));

elseif(RX(i-1) >= 0.1)

cdu(i-1)=(24/RX(i-1))+4.5;

elseif(RX(i-1) >=0.0001)

cdu(i-1)=24/RX(i-1);

end

end

plot(x,y)