[ESPResSo-users] Inability to replicate a specific type of fluid flow.

[Harmanjit Singh]

Dear All,

I can not replicate a fluid flow where in after a cylindrical obstacle, secondary vortices form (something similar to http://fluidsengineering.asmedigitalcollection.asme.org/data/Journals/JFEGA4/926053/091102_1_f5.jpeg ). The Stream lines (visualized in paraview) all flow unbroken from source to sink, i.e. there is no vortex after obstacle and i am inclined to believe there should be (I only get the fluid flow of the first kind as shown here http://media-1.web.britannica.com/eb-media/22/2522-004-E94C5246.jpg but i don't get fluid flow of second kind). I have played around with the density, viscosity and velocity values but to no avail.

I am curious is this type of behavior possible in Lb-fluid Simulations in Espresso3.3.0? If it is, please guide me how can I simulate it.

Thanks and Regards

Harmanjit

Script (ran on version 3.3.0):

setmd time_step 0.1; setmd skin 0.5
set boxX 30; set boxY 30; set boxZ 120
setmd box_l $boxX $boxY $boxZ
lbfluid gpu agrid 1.0 dens 1.0 visc 8 tau 0.1 friction 0.8
source boundaries.tcl
lbboundary rhomboid velocity 0 0 0.05 corner 1 [expr {7*$boxY/8}] 1 a [expr $boxX-1] 0 0 b 0 [expr $boxY/8] 0 c 0 0 1 direction 1
set steps 200; set counter 0
while { $counter<50} {
    set cycle [expr $counter*$steps]
    puts "cycle $cycle"
    lbfluid print vtk velocity "output/fluid$cycle.vtk"
    integrate $steps
    incr counter
}