CFD and DEM - General Discussion

Hello guys!

I wonder if it possible to simplify a bit the captcha pictures, because they are almost impossible to read, and thus it is discouraging us to answer posts !

Cheers,Joris

Hi !

I have such a stupid question I wonder if this is the right place to ask !
The pressure directory CFD/0/p contains pressure setting.
Since I see 1.e05 in both Hopper and Ergun testcases, I assume it uses Pascal Unit (as 1 atm = 10^5 Pa).

Since [Pa]=[kg/(m*s^2)], bracket unit should be [1 -1 -2 0 0 0 0] and NOT [0 2 -2 0 0 0 0], isnt it???

li fang

Hello,
i am simulating a lid cavity case:
periodic BC on X,
upper wall is moving with 1. m/sec
an obstacle is placed on the middle of lower wall
other particles are vibrating due to LJ interaction.

what is the optimal way to obtain no-slip BCs on wall and obstacle, ( indent or fix wall/reflect) ?

Hallo ,
i am almost new to LIGGGHTS , i am running a simulation of a box (3d) , i apply a velocity to the top lid
while keeping the initial velocities zero at the begining ,
i started understanding (flow2 example in LAMMPS directory ) ,
i have a question , why when i change the lattice factor , i get my particles penetrating the implemented wall !?
- how can i prevent the particles from penetration the walls and not being lost and also avoid my whole domain to be scaled during simulation (since i use s as boundary condition ?!

i am student of aerospace engineering and i working over rarefied gas dynamic flow. with your point view can i use of CFDEM or LIGGGHTS for my working field ?
help me please
thanks a lot
esmaeil

Hi ALL

I'm curious as to who is using LIGGGHTS, what their backgrounds are and why they're using it. I'm a mechanical engineer working in industry. We use FEA but don't have any requirement for DEM. My interest is mostly as a hobbyist, although I would like to eventually write my LIGGGHTS use up as a proposal for a MEng degree.

Regards

Rolling firction for DEM
1.
Assessment of rolling resistance models in discrete element simulations Original Research Article
Powder Technology, Volume 206, Issue 3, 30 January 2011, Pages 269-282
Jun Ai, Jian-Fei Chen, J. Michael Rotter, Jin Y. Ooi

Time step selection
1.
Catherine O'Sullivan, Jonathan D. Bray, (2004) "Selecting a suitable time step for discrete element simulations that use the central difference time integration scheme", Engineering Computations, Vol. 21 Iss: 2/3/4, pp.278 - 303

I am using Hertz contact in LAMMPS. Would some body please let me know a set of equations that I can use to compute normal and tangential stiffness, normal and tangential dumping coefficients from material constants like E, G, mu. Thank you in advance

I am a newer here, and I want to know if the LIGGGHTS DEM Code can be easily coupled with a commercial CFD software? then can be used to simulate the spouted bed?

As a beginner to DEM and granular dynamics I am interested in knowing the equations LIGGGHTS is solving for fluid flow and phase transfers. I'm familiar with Navier-Stokes, however the CFD-DEM portion on this site refers to a 'volume fraction' introduced to account for the granular particles; and to phase transfers of energy, mass, and momentum. I assume the particle-particle interactions are treated with MD Hertz force law solving for F = ma.