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### Messages - moloy_kb

Pages:  2
1
##### Fluent / Time dependent source term
« on: September 06, 2012, 06:44:11 AM »
Dear all,

I am trying to solve the effect of body acceleration on the human arterial system. For that I need to write some codes for a time dependent source term in DEFINE_SOURCE Macros. The acceleration term is given by
a(t) = a0*Cos(omega*t+Phi), where a0 is the amplitude part of the acceleration in mm, but the Fluent document tells that the dimension of the source term should be in N/m^3. How to make the proper dimension for the problem.

2
##### Fluent / moving wall problem
« on: August 24, 2012, 08:31:49 AM »
Dear all,
I want to simulate the flow through a pipe in Fluent whose wall is moving in sinusoidal manner along normal direction. Please help me in this regard. I am also attaching the geometry of the problem.

3
##### Fluent / Porous media in Fluent
« on: July 12, 2012, 11:04:05 AM »
Dear all..
Please find the attached document, where I clearly mentioned about the problem that I am facing regarding the formulation of the problem.
Any help is highly appreciated.

4
##### Fluent / non newtonian viscosity problem
« on: June 27, 2012, 11:23:50 AM »
Dear all,
I am simulating the problem of blood flow through an artery in 2D considering laminar flow. For this I am using the Walburn and Scneck model to define the blood viscosity using the equation:
mu_lam=K*(strain)^(n-1), where K=14.67*10^(-3) and n=0.7755. In order to define the viscosity I am using the following UDF:
#include "udf.h"
DEFINE_PROPERTY(cell_viscosity_power_law,c,t)
{
double mu_lam;
double strain;
double muinf = 14.67e-3;
double n = .7755;
strain = pow(C_DUDX(c, t),2)+ pow(C_DVDY(c, t),2)+
2*pow(C_DUDY(c, t)+ C_DVDX(c, t),2)+
2*pow(C_DUDZ(c, t),2)+
2*pow(C_DVDZ(c, t),2);
strain = pow(strain, 0.5);
strain =fabs(strain);
mu_lam=muinf*pow(strain,n-1);
return mu_lam;
}
But, once I try to solve it the solver gives the error: Divergence detected in the AMG solver.

5
##### Fluent / Re: Outlet Boundary condition
« on: June 08, 2012, 10:59:28 AM »
thanks for the reply, it works properly.

6
##### Fluent / Outlet Boundary condition
« on: June 08, 2012, 07:46:50 AM »
Dear all,
I am simulating the laminar flow through a pipe having one(1) inlet and ten(10) outlets. As a boundary condition I am prescribing the inlet velocity for the inlet plane. For the outlets, I know the value of outflow discharges as a percentage of the inlet flow like

Inlet:100%       outlet1: 20%
outlet2:5%
outlet3:10%
outlet4:5%
outlet5:11%
.....
But, how to put this boundary condition in Fluent.

7
##### Fluent / Re: Particle injection in DPM
« on: June 08, 2012, 07:46:13 AM »
Thnks.. It works

8
##### Fluent / Particle injection in DPM
« on: May 29, 2012, 07:32:48 AM »
Dear all,
I am doing the unsteady DPM calculation and there I want to inject particle in the domain at every alternate particle time step. How to do it??

9
##### Fluent / Particle Plot
« on: April 27, 2012, 05:06:01 AM »
I am doing DPM to track the particle on the wall of a 3D pipe. How to plot the location of the trapped particle only on the surface of a pipe?

10
##### Fluent / Histogram plot in DPM
« on: April 27, 2012, 05:03:32 AM »
Dear All,
I am doing one unsteady particle tracking using transient flow. For analysis of particles that are trapped in the target zone, i open the sample file and plot the histogram. The result gives quite satisfactory when we plot all the x-loc of the trapped particle in the histogram. But when I plot the time variable histogram, the plot is not quite understandable.
If anybody worked on this please explain the meaning of time variable in the dpm histogram sample file variable list.

11
##### Fluent / Re: Coordinates of discrete phase in lagrangian approach using UDF
« on: April 27, 2012, 04:37:53 AM »
I am doing unsteady particle tracking and from the known location of each particle at any instant of time within the domain I have to calculate one interactive force which is a function of the position vector of each particle. Suppose in the domain at any instant of time say 50 particles are there. So, interactive force on suppose, 10th particle is a function of radius vector of all the other particle (i.e, 49 particles) measured from the center of the 10th particle.
For, this force calculation I need the location of individual particle.
Another question is that for this type of analysis if we perform steady tracking is it possible to know the location of each particle?

12
##### Fluent / Re: Coordinates of discrete phase in lagrangian approach using UDF
« on: April 26, 2012, 05:35:56 AM »
Dear pitney1
Thanks for your reply. I can also run the udf, but the problem is that I wants to know the instantaneous location of all the particles inside the domain. But from the file it is quite difficult to find what is the location of say 10th particle?So, how to sort it out that the location of each particle against the particle ID.
Pl. help me in this regard....

13
##### Fluent / Re: Coordinates of discrete phase in lagrangian approach using UDF
« on: April 25, 2012, 11:30:34 AM »
Dear piso
I am trying to do what u have mentioned in that thread. But my problem is when I try to write the location of each particle along with the ID of the tracked particle, it will give some erroneous result.
Bellow I am giving my UDF. I should know the exact location of each particle at any instant of time within the domain, so that with this information I can calculate the force.

#include "udf.h"
#define PI 3.14159               /*Assighned value for Pie*/
#define R_imp 1e-6               /*Radius of the Implant*/
#define mu_imp 2      /*Relative permeability of the Implant material*/
#define Tesla .6               /*Product of u0*H0*/
#define xfmp .4               /*weight fraction of froomagnetic material in MDCP*/
#define rhofmp 7850               /*Density of the ferromagnetic material*/
#define rhopol 950               /*Density of the binding polymer*/
#define r_mdcp 50e-9            /*radius of MDCP*/
#define Mfmp_s 1.735e6            /*Saturation Magnetization of Ferromagetic material*/
#define Bolt_const 1.3806503e-23   /*Boltzman constant*/
#define Temp 309               /*Absolute Temperature*/
real x,y,theta;
real Numr1,Dnmr1,Term1,Numr2,Dnmr2,Term2,Term3,Numr3,Numr4,Numr5,Numr6,Dnmr3,Dnmr4,Dnmr5,Dnmr6;
real Term_sq,C1,Del_Phi_del_x,Del_Phi_del_y,Del2_Phi_del_x2,Del2_Phi_del_y2,Del2_Phi_del_xy;
real B_x,B_y,mod_B;
real Del_Bx_delx,Del_Bx_dely,Del_By_delx,Del_By_dely;
real wfmp_denom,wfmp_numr,wfmp;
real V_p,beta_numr,beta_dnmr,beta1,beta,Lan_beta;
real moment1,moment2,moment3,moment4,moment_x,moment_y;
real Fmx1,Fmx2,Fmx,Fmy1,Fmy2,Fmy,bforce;
float x1,y1,z1;
DEFINE_DPM_BODY_FORCE(particle_body_force,p,i)
{
FILE *pf;
theta=0;
x=P_POS(p);
y=P_POS(p);
Term_sq=(x*x+y*y);
x1=p->state.pos;
y1=p->state.pos;
z1=p->state.pos;

if(NULL == (pf = fopen("particle_position.txt","a")))
Error("Could not open file for append!\n");
fprintf(pf,"%d\t%e\t%e\n",p,x1,y1);
fclose(pf);
/*calculation of Term1 in expression of Phi*/
Numr1=mu_imp-1;
Dnmr1=mu_imp+1;
Term1=Numr1/Dnmr1;
/*calculation of Term2 in expression of Phi*/
Term2=R_imp*R_imp;
C1=Term1*Term2;
/*calculation of Dphi/dx*/
Numr2=((cos(theta)*(y*y-x*x))-(2*x*y*sin(theta)));
Dnmr2=Term_sq*Term_sq;
Del_Phi_del_x=C1*Numr2/Dnmr2;
/*calculation of Dphi/dy*/
Numr3=((sin(theta)*(x*x-y*y))-(2*x*y*cos(theta)));
Dnmr3=Term_sq*Term_sq;
Del_Phi_del_y=C1*Numr3/Dnmr3;
/*calculation of D2phi/dx2*/
Numr4=((x*cos(theta)*(x*x-3*y*y))+(y*sin(theta)*(3*x*x-y*y)));
Dnmr4=Term_sq*Term_sq*Term_sq;
Del2_Phi_del_x2=2*Tesla*C1*Numr4/Dnmr4;
/*calculation of D2phi/dy2*/
Numr5=((x*cos(theta)*(-x*x+3*y*y))+(y*sin(theta)*(-3*x*x+y*y)));
Dnmr5=Term_sq*Term_sq*Term_sq;
Del2_Phi_del_y2=2*Tesla*C1*Numr5/Dnmr5;
/*calculation of D2phi/dxdy*/
Numr6=((y*cos(theta)*(3*x*x-y*y))+(x*sin(theta)*(3*y*y-x*x)));
Dnmr6=Term_sq*Term_sq*Term_sq;
Del2_Phi_del_xy=2*Tesla*C1*Numr6/Dnmr6;
/*calculation of B*/
B_x=(Tesla)*cos(theta)-(Tesla)*Del_Phi_del_x;
B_y=(Tesla)*sin(theta)-(Tesla)*Del_Phi_del_y;;
mod_B=sqrt((B_x*B_x)+(B_y*B_y));
/*calculation of volume fraction*/
wfmp_denom=(xfmp+((1-xfmp)*(rhofmp/rhopol)));
wfmp_numr=xfmp;
wfmp=wfmp_numr/wfmp_denom;
/*calculation of volume of MDCP*/
V_p=(4/3)*PI*(r_mdcp*r_mdcp*r_mdcp);
/*calculation of Beta*/
beta_numr=wfmp*V_p*Mfmp_s;
beta_dnmr=Bolt_const*Temp;
beta1=beta_numr/beta_dnmr;
beta=beta1*mod_B;
/*calculation of langevin function*/
Lan_beta=1/(tanh(beta))-1/beta;
/*calculation of magnetic moment*/
moment1=wfmp*V_p*Mfmp_s;
moment2=Lan_beta;
moment3=mod_B;
moment4=(moment1*moment2)/moment3;
moment_x=moment4*B_x;
moment_y=moment4*B_y;

if(i==0.)

{
Fmx1=moment_x*Del2_Phi_del_x2;
Fmx2=moment_y*Del2_Phi_del_xy;
Fmx=Fmx1+Fmx2;
bforce=-Fmx;
}
else if(i==1.)
{
Fmy1=moment_x*Del2_Phi_del_xy;
Fmy2=moment_y*Del2_Phi_del_y2;
Fmy=Fmy1+Fmy2;
bforce=-Fmy;
}
return(bforce/P_MASS(p));
}

14
##### Meshing / Re: conv-div nozzle geometry
« on: April 25, 2012, 04:51:03 AM »
Thanks for the tutorial, but what I am asking that, how to draw the geometry, when the equation of the profile is given?

15
##### Meshing / conv-div nozzle geometry
« on: April 07, 2012, 10:40:53 AM »
Hi,
How to draw the convergent divergent shaped nozzle, in which the variation of area is given by A=0.1+2.58x^2, using Ansys 13 Design Modeller.