circular cylinder

Lattice Boltzmann Method LBM: Theory
#1

Hi Dear All,
I hope every one will be fine. Dear all i need a kind help if any one can.
Can any one have idea about the following two things.

  1. I read some papers they given the values about recirculation length and width for circular cylinder. How we can compute these values if we have the graphs in the form of vorticity contour lines and in the form of stream lines.
  2. Can any one have a piece of code using Fortran that how to set the geometry of circular cylinder in Fortran to draw the graphs of vorticity and stream lines using TECPLOT.
    Best Regards and bye for now.
    Khan
#2

i don’t have an answer but i’m curious. what’s the formal definition of the recirculation length and width?

#3

Hi Dear Friend Adam,
If you read this article “Steady incompressible flow past a row of circular cylinders , J. Fluid Mech. 225 (1991), 655-671” In this paper the author discuss about the length and width of recirculation region.
I try to find the same thing and try to using matlab but i not get it may be i do some mistakes using matlab. I calculate like this once i have the data.
Using Matlab, wha t I probably would do would be to first use Matlab’s interp2 routine (with the option ‘cubic’) to get the computed data to a finer grid. And then use Matlab’s contour routine to get points along the zero cont our line. From the vector of data that returns from that i want to find the maximum value of surface vorticity, length and width of recirculation region.
Dear friend you have any idea how to find these values.
Thanks and Best Regards
Khan

#4

i read the paper but didn’t find an exact mathematical definition of “recirculation zone”. do you know the definition? otherwise, the only solution is probably to ask the authors directly. once you know, we can go on and try to find a matlab script which calculates width and length of the zone. anyway, please tell us if you find the answer, i’ve become curious now.

#5

Hi dear all
I didn’t read this article, but i think u can read the x velocity in centerline, the position that the x velocity get zero, from plus value to minus! This position is the recirculation length if the coordinate located in center of cylinder!!(it should be the steady)