# for loop inside a cell_loop?

 Register Blogs Members List Search Today's Posts Mark Forums Read September 26, 2007, 22:24 for loop inside a cell_loop? #1 MHDWill Guest   Posts: n/a Hi all, I was wondering if there's something I have to keep in mind when I'm doing a for loop inside a predefined loop macro for FLUENT. Basically I'm trying to generate a magnetic field by adding up magnetic field contribution from multiple sources. I create these multiple sources through a for loop inside a cell loop. All constants are defined at the beginning of the code using #define, int, and/or real (#define isn't shown in the code below). Basically, I have a lot of helmholtz coil in the system located along the z-axis. At each cell centroid, I want to calculate the magnetic field contribution from all the coils, hence I use the for loop inside the cell_loop macro. I calculate the contribution of i'th coil and add them up. bix, biy, biz is the magnetic field contribution at each cell due to all the coil. So, after the iteration is done, I assign C_UDMI(c,t,0)=bix, C_UDMI(c,t,1)=biy, C_UDMI(c,t,2)=biz to define the magnetic field strength at each cell centroid. But when I do this and generate a contour plot, the magnetic field is somewhat uniform rather than what we expect to see in a helmholtz coil. Is there a problem how I define the variables in int and real? The code is shown below. DEFINE_INIT(Define_B_Field,d) { int i; real dx, theta, phi, px, p, x[ND_ND],r, rx, rhomag, themag, ci, ct, co, bix,biy,biz ; Thread *t; cell_t c; ci = ri*ri/fabs(nix); constant co = ro*ro/fabs(nox); constant ct = (pow(ci*nix,0.5)-rt)/(nix*nix); constant dx=lsys/nc; /*increment between coils in meters */ /*Now calculating magnetic field @ each cell centroid*/ thread_loop_c(t,d) { begin_c_loop(c,t) { C_CENTROID(x,c,t); bix=0.0; biy=0.0; biz=0.0; for (i;i<=nc;i++) { rx= -lsys/2 + (i-1)*dx; if (rx < cp) { r = pow(ci*fabs(rx),0.5); } else if (rx > cp & rx < dp) { r=ct*rx*rx+tzp; } else if (rx > dp) { r = pow(co*fabs(rx),0.5); } px=x-rx; /*x-coordinate of the cell centroid with respect to the current (i'th) coil center*/ p=pow(px*px + x*x + x*x,0.5); /*Position vector magnitude of cell center from center of the "i'th" Helmholz coil*/ theta=atan2((pow(px*px+x*x,0.5)),x);/*Longitudinal angle from z-axis*/ phi = atan2(x,px); /*Azimuthal angle in the xy-plane with respect to z-axis*/ rhomag= pow( cos(theta)*cos(phi)*cos(theta)*cos(phi) + sin(theta)*sin(phi)*sin(theta)*sin(phi)+cos(theta) *cos(theta),0.5); themag= pow( p*p*(sin(theta)*sin(phi)*sin(theta)*sin(phi) + cos(theta)*sin(phi)*cos(theta)*sin(phi)+sin(theta) *sin(theta)),.5); bix +=permeability*(I/2*r*r*cos(theta)*(1+(15*r*r*p*p*sin(theta)*sin(the ta))/(4*pow(r*r+p*p,2)))/(pow(r*r+p*p,3/2))*cos(theta)*sin(phi)/rhomag-I/4*sin(theta)*(2*r*r - p*p +(15*r*r*p*p*sin(theta)*sin(theta)*(4*r*r - 3*p*p)/(8*pow(r*r + p*p,2))))/(pow(r*r + p*p,5/2))*p*sin(theta)*sin(phi)/themag); /*x-component of magnetic field for each helmholtz coil*/ biy +=permeability*(I/2*r*r*cos(theta)*(1+(15*r*r*p*p*sin(theta)*sin(the ta))/(4*pow(r*r+p*p,2)))/(pow(r*r+p*p,3/2))*sin(theta)*sin(phi)/rhomag-I/4*sin(theta)*(2*r*r - p*p +(15*r*r*p*p*sin(theta)*sin(theta)*(4*r*r - 3*p*p)/(8*pow(r*r + p*p,2))))/(pow(r*r + p*p,5/2))*p*cos(theta)*sin(phi)/themag); /*y-component of magnetic field for each helmholtz coil*/ biz +=permeability*(I/2*r*r*cos(theta)*(1+(15*r*r*p*p*sin(theta)*sin(the ta))/(4*pow(r*r+p*p,2)))/(pow(r*r+p*p,3/2))*cos(theta)/rhomag+I/4*sin(theta)*(2*r*r - p*p +(15*r*r*p*p*sin(theta)*sin(theta)*(4*r*r - 3*p*p)/(8*pow(r*r + p*p,2))))/(pow(r*r + p*p,5/2))*sin(theta)*p/themag); /*z-component of magnetic field for each helmholtz coil*/ } C_UDMI(c,t,0)=bix; C_UDMI(c,t,1)=biy; C_UDMI(c,t,2)=biz; } end_c_loop(c,t) } } Thread Tools Search this Thread Show Printable Version Email this Page Search this Thread: Advanced Search Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules Similar Threads Thread Thread Starter Forum Replies Last Post Helmi FLUENT 0 February 4, 2011 05:54 vetnav Tecplot 4 July 14, 2010 21:03 allenzhao OpenFOAM Installation 127 January 30, 2009 20:08 Marios Vlad CFX 1 February 6, 2008 08:11 Steve FLUENT 0 April 17, 2003 13:37