seabrookzzz / hemodynamic-calculator

Calculator for hemodynamic parameters using exported Fluent ASCII data. Specifically: TAWSS, OSI, RT, and transWSS.

Hemodynamic Calculator

This code was made to work with MATLAB R2020b

What are TAWSS, OSI, RRT, and transWSS?

Time averaged wall shear stress (TAWSS) refers to fluid flowing parallel to a surface, causing a shear stress on it. This stress has been reported to be important in vascular remodeling.

Similarly, He and Ku (1996) found that not only was the amount of stress on the tissue surface important but its direction, leading them to create the Oscillatory Shear Index (OSI) metric to quantify the degree to which fluid is moving forward or backwards on a surface.

Relative residence time (RRT) is a marker of disturbed blood flow and quantifies the degree to which blood is in a low shear but high oscillation state. Meaning relatively how long will a particle of blood stay at a certain location compared to other particles.

Transverse WSS (transWSS) is similar to TAWSS but rather than being constrained to parallel flow it looks at multidirectional disturbed flow and it's time-average results over the normal of a surface.

More information regarding TAWSS and OSI can be found in the reference given below.

1. Hsu CD, Hutcheson JD, Ramaswamy S. Oscillatory fluid-induced mechanobiology in heart valves with parallels to the vasculature. Vasc Biol. 2020 Feb 17;2(1):R59-R71. doi: 10.1530/VB-19-0031. PMID: 32923975; PMCID: PMC7439923.

What does this code do?

It processes Fluent exported ASCII data for Wall Shear Stress and XYZ Wall Shear Stresses and then reports back the parameters along with a plot of the surface.

Example data and a PowerPoint detailing how to use the script is provided as a reference.

How does it do it?

For each time step the code iterates across all nodes and does a temporal integral from 0 to T. The formulas used are shown below:

TAWSS

OSI

RRT

transWSS

Feel free to fork this on GitHub