Shear rate fluctuation and calculating the viscous stress tensor

[ahmedelhanafy2022]

Hello all,
I have read two published papers that are based on HemoCell and I have two inquiries about the obtained results:

The first paper: Haemodynamic flow conditions at the initiation of high-shear platelet aggregation: a combined in vitro and cellular in silico study

I found that there are high fluctuations in the shear rate obtained in Fig.9. Is there an explanation for this behavior?

The second paper:The effect of stiffened diabetic red blood cells on wall shear stress in a reconstructed 3D microaneurysm

Regarding Eq. 1 for calculating the viscous stress tensor, where can I find it in HemoCell output ?
Do you have any idea about that?
Regards
Ahmed

[gzavo]

Hi @ahmedelhanafy2022,

I found that there are high fluctuations in the shear rate obtained in Fig.9. Is there an explanation for this behavior?

I assume you mean the light blue and light red curves. The fluctuation is due to the cellular nature. When a cell passes close to the wall the shear stress imposed on the wall is increased.

Regarding Eq. 1 for calculating the viscous stress tensor, where can I find it in HemoCell output ?

Look at some of the relevant tensors quantities you can output by adding them to the ‘hemocell.setFluidOutputs’ function arguments:

HemoCell/io/FluidHdf5IO.hh

Lines 184 to 198 in 3189621

	case OUTPUT_SHEAR_STRESS:
	output = outputShearStress();
	name = "ShearStress";
	dim[3] = 6;
	break;
	case OUTPUT_SHEAR_RATE:
	output = outputShearRate();
	name = "ShearRate";
	dim[3] = 9;
	break;
	case OUTPUT_STRAIN_RATE:
	output = outputStrainRate();
	name = "StrainRate";
	dim[3] = 6;
	break;

Computing it manually from the velocity field is also a (more laborious) option.

[ahmedelhanafy2022]

That's great!
Many thanks Dr. @gzavo.
It seems to be a trivial question, could you tell me how can I add them?
I tried to find it in HemoCell/core/hemoCell.cpp but I could not

[ahmedelhanafy2022]

Finally, I got it!
It can be found in cpp file of each case.
Many thanks @gzavo