Hi, all Lammps users.
I come across several questions about using dpd to simulate a poiseuille flow.Just a few days ago, I've asked the same question and got answer from Axel, Samuel and Steve, I appreciate their kindly help.However, I still have some questions, as follows:
1. dpd contains a thermostat, so I can't use pair_style dpd and pair_style dpd/tstat at the same time,right? { When I use dpd + nve, the flow temperature in y direction is not 1.0 as I expected. However, when I use dpd+nve +dpd/tstat (I guess I use twice dpd thermostat), the temperature in y direction is exactly 1.0, however,the flow velocity is beyond the analytical velocity. }
2. I am confused by compute temp/partial and compute temp/profile. Both computes remove velcity bias in some dimension before compute temperature, what's the difference? Accroding to answer from Axel, Samuel and Steve last time, I know that I needn't to exclude a velocity bias from a dpd flow, since dpd as a thermostat works on relative velocity of 2 atoms in a pair. Is this means that if I use a compute/partial to calculate temperature of the system, I will get the wrong result?
3. I want to set the flow temperature to 1.0, is this means that temperature in y direction is exactly 1.0 or some temperature fluctuation is allowed near the wall?
4. I feel dpd as a thermostat can't fulfill my target-- right flow velocity and right temperature. So I have to use another thermostat or I have to change the weight function w(r) in the dpd function?
These question seems too naive, but they have confused me for weeks. I hope if any one can give me some suggestions. Thank you very much!
2013-07-17
Xiaojun Li
Biomechanics and Biomaterials Laboratory
Department of Applied Mechanics
School of Aerospace Engineering
Beijing Institute of Technology
Beijing 100081, P. R. China
Email: [email protected]...
in.smallmodel-nve8 (3.25 KB)