Heres a fortran code to solve the equation of motion of very small
particle in a low reynolds number flow. It is not working in all
compilers, I have a working version of this code, but it doesnt work
for all inputs. Can someone tell me what is wrong with this and fix it
so that it works for a stokes number of 0.1 through 2. Stokes number
is calculated in the program. You need to work backwards by playing
with the input file and see for what values of input the stokes number
is 0.1 through 2.

my particle hardly moves. I have no way of even telling if my values
are correct. What should I do? Pls help.
my input file. it contains values of t_max, alpha, Rho, Rp, Rf, Uf in
that order exactly
example working input file values are:
600,0.05,2165,3.00E-07,5.20E-06,0.003 in that order.

source code:

IMPLICIT NONE
REAL*8 DERIV_FX,
DERIV_FY,N,RP,RF,RHO,UF,alpha,K,R0,U
REAL*8
Nu,x,y,y0,THETA,DT,T0,UT0,PI,T,THETA0,Stokes
...

In article <2536c6bf-4017-43c3-aa00-5d9eb8dd305e@u72g2000hsf.googlegroups.com>,
madhu0319@gmail.com writes:

....

madhu0319@gmail.com wrote:

On Mar 26, 8:57 pm, madhu0...@gmail.com wrote:

On Mar 26, 8:19 pm, ka...@troutmask.apl.washington.edu (Steven G.
Kargl) wrote:

Thankyou, is there any way i can attach files here? I have an exe file
for the code above, but i dont know if it returns correct values, i
dont anything abt coding. i am a zero. this is another guys work that
i have to improve. i have to get better results and submit it..is this
program feasible in a time frame of 20days?or is it entirely wrong.

heres what is going on in the program..

What basically we are doing is tracking a particles trajectory and
checking if it’s hitting a fiber filter that we have. It’s a low
Reynolds number flow. That program is not working at very small stokes
number and at every particle velocity. So I have to alter the
program.

For the particle trajectory we are solving an equation

dv/dt= 18 * η*(U-V) / (2rp )2 ρp
---------------------------------------- equation 1
where η = (2*RP)^2*RHO*UF/ (6*PI*Nu*2*RF)
This is also the equation 4.19 of the textbook that the program
refers to while solving.

The program goes like this

i did not use any diagnostic program. i dont even know anything abt
it. i dont know anything abt fortran or coding..this is my project at
school thats due in 20days..cani run this code on any compiler, i mean
is it compatible with any? shud it return the same values on any
compiler?

pls bear with my silly questions, i am very stressed out abt this..

In article <4e374a6d-1203-40a2-8b15-216aa141ea8d@x41g2000hsb.googlegroups.com>,
madhu0319@gmail.com writes:

On Mar 26, 10:08 pm, madhu0...@gmail.com wrote:

You CAN get your program to compile if you

1. remove leading spaces on each line
2. change

EXTERNAL FX, FY, DERIV_FX, DERIV_FY

to

EXTERNAL FX, FY

3. compile as free format source

DERIV_FX and DERIV_FY are variables NOT functions passed as arguments
to routines so there is no need to make them EXTERNAL.

If the program becomes exhausted and can't make it to 5, maybe it will
just fall into STOP.

Good suggestions. Reminds me of my old old old old college days.

On Wed, 26 Mar 2008 21:21:53 -0700 (PDT), e p chandler juno.com>
wrote: