# Simulating capillary filling in microfluidic channels

Hello everyone,

Just got introduced to simscale for simulation. The step-by-step tutorials has been great. I was wondering if I could simulate capillary filling of micro channels using simscale.
I am currently on the free community-tier.

Thanks

Hi flmax,

I guess for this you would need to use the multiphase solver.

But I’m not quite sure if capillary is included in this solver. And I’m not aware of such a project within the community.

Best regards
Sebastian

Hi 4flmax & welcome,
An interesting topic on the filling of micro channels…

I did some searching on Simscale documentation and google as this is outside my experience, but I found this… It appears that " The lattice Boltzmann method (LBM) is a relatively new simulation technique for complex fluid systems and has attracted great interests from researchers in computational physics and engineering. Unlike traditional computation fluid dynamics (CFD) methods to numerically solve the conservation equations of macroscopic properties (i.e., mass, momentum, and energy), LBM models the fluid as fictitious particles" Lattice Boltzmann Method (LBM) | SpringerLink

Ok, well Simscale also provides LBM solvers, but I don’t recall any on Microfluidics applications. I did a search on the Simscale public projects and found several that had undertaken simulations.

I found this in Simscale Documentation…

The Navier-Stokes equations cannot compensate for the physical model of the flow at very small scales such as the motion of single bacteria — also called microfluidics. Thereby, it is convenient to either change or reinstate the Navier-Stokes model with a suitable mathematical model. The Knudsen number (Kn) is a dimensionless number that is the ratio of the mean free path of molecular structure to the observation scale. The preferred model in accordance with the Knudsen number is shown in Figure 6:

But I recall seeing a public project similar to this paper which might be of interest as well, which applies conventual CFD, https://www.ese.wustl.edu/~nehorai/research/molec_imaging/FEM.html

But as I said earlier, the LBM is available in Simscale, but it seems to have been applied to building environments.