Recent content by Wisam

Thank you for your help. We know the normal for spherical particle ( for sphere we know how the normal) but I need to find the normal for non-spherical shape. If we say the radius r=R(t)+epsilon R(theta,t) then how can I find the normal for that form.? I think the normal will be n=n0+epsilon n1...

Thank you for your help. We know the normal for spherical particle ( for sphere we know how the normal) but I need to find the normal for non-spherical shape. If we say the radius r=R(t)+epsilon R(theta,t) then how can I find the normal for that form.? I think the normal will be n=n0+epsilon n1...

Let's say we have r=R( theta, phi, t) on the surface of the particle and need to find the normal vector in Spherical Coordinate system. We know that, the unit vector =grad(r-R( theta, phi, t)) / |grad((r-R( theta, phi, t))| where grad is Spherical gradient operator in term of e_r, e_\theta...

Thank you BvU and ##\delta(t)## is represent a time-dependent. I hope someone can help me in this...

Dear BvU, Thank you for your replay, yes the equation is right. The field equation is diffusion equation with 2 free boundary conditions I applied the Fourier transform for the diffusion and the boundary conditions and finally i got this first ODE I stuck on it ? any idea please?

Can anyone help me to solve a differential equation? I want to solve ∂v(p,t)/∂t=-p^2 v(p,t)-sqrt(2/pi)∫v(p,t)[1-δ(t)R(t)]dp+sqrt(2/pi)[δ(t)R^2(t) C] with initial data v(p,0)=0 where C is constant and the integration from zero to infinty Any suggestion please? Solution by volterra integral...

Hi there I need to know the density, viscosity, heat capacity,and temperature for the oil or crud oil? Also I need to know the wall temperature for pipe? Can anyone help me please ?

Hi there Can anyone tell what is the meaning of boundary conditions for temperature distribution in a flowing viscous fluid in a pipe ? for example I need some one explane for me this: T = T1 at r = R, x<0 T = T0 at x = 0, r<R where T1 is a temperature of well and T0 is a temperature...