Hi,

I am a beginner with LBM and trying to work on bloodstain pattern analysis.

I want to simulate spherical droplets of blood impacting a solid surface.

the density of blood is approximately 0.00475 kg/m3 and this is happening in air surrounding the droplet.

solid surface(glass, wood, etc) can be changed depending upon the contact angle.

I dont know how to start with this method. can anyone help me please.?

has anyone worked with droplets impacting a solid surface?

any help is highly appreciated.

Regards,

Gulraiz

Hello,

the density of blood is 1030 kg/m[sup]3[/sup], and the viscosity is about 3 cP at high shear rates.

You will need a multi-component or at least a multi-phase approach, e.g., Shan-Chen.

Your task sounds interesting, but I have never seen drop impact simulation with LBM. However, in my group, some people investigate the motion of droplets on surfaces via LBM.

Best regards,

Timm

hi,

sorry that was the viscosity. the density is around 1060kg/m3.

i know that this is a multiphase problem. i need to know how to go about it.

i have started to read this book “Lattice Boltzmann Modeling -An Introduction for Geoscientists and Engineers”

is it a good starting point?

can you introduce me to those people? may be they can suggest something.

Regards,

Gulraiz

You do not have any LBM background? I would first read a bit in the book. I will ask my colleagues if they have some idea or know any references. I know that they have only simulated the viscous regime of droplet motion, i.e., for small Reynolds numbers. I will tell you when I know more.

Timm

Have a look at this article: Lee, Liu. Lattice Boltzmann simulations of micron-scale drop impact on dry surfaces. J. Comput. Phys. 229 (2010) 8045-8063.

This is all I can give you.

Timm

thank you timm. i have gone through this paper. i need to ask you that whether this problem is possible with LBM? as the density ratio is more than 1000 and I have read somewhere that LBM is not stable at high density ratios?

Gulraiz

Hello,

I don’t do the two-phase flow, I don’t know whether it can help:“A lattice Boltzmann method for incompressible two-phase flows on partial wetting surface with large density ratio, Y.Y. Yan, Y.Q. Zu / Journal of Computational Physics 227 (2007) 763–775”.

Best,

X.F.Shi

I am not expert in multi-phase or multi-component flows. But I know that high density ratios are possible. A factor of 1000 is not a problem under some circumstances. It depends on the underlying multi-phase model. Please be aware that there are different multi-phase models available for LBM.

Hello,

As I wrote in the PM you need first to identify the nondimensional parameters which describes your physics problem. Currently I’m doing microchannel simulations with binary liquid model and I’m able to simulate like air finger propagation for small capillary numbers with uniform density model (even the density ratio for air and liquid is around 1000). Gas-liquid ratio in some problems are not important.

I would certainly start with the underlying physics and then identify the necessary LBM model to be used.

Hopefully it will help,

Alex