ICFD solver and pressure

[Guillaume RENEDO]

Hello everyone,

I have a question regarding the ICFD solver in LS-DYNA.

I am currently working on hemodynamic modeling in arteries using the fluid-only solver (no mechanical coupling for FSI).
I am using the *ICFD_BOUNDARY_WINDKESSEL card for my boundary conditions.

However, I am wondering about one particular point and would appreciate your feedback.

In hemodynamic simulations with LS-DYNA, do you work with realistic absolute pressure values (physiological arterial pressure in mmHg), or do you instead work with relative pressures and physiological pressure differences?

For example:

1. I tune my Windkessel resistances (R) to work with an absolute mean arterial pressure of 100 mmHg and a systolic/diastolic pressure difference of 50 mmHg
   (P_{systolic} = 140 mmHg and P_{diastolic} = 90 mmHg)

or

2. I tune my Windkessel resistances (R) to work with a relative mean arterial pressure of 0 mmHg and a systolic/diastolic pressure difference of 50 mmHg
   (P_{systolic} = 33 mmHg and P_{diastolic} = -17 mmHg)

I am having difficulties tuning my resistances, and the solver diverges when I try to simulate physiological absolute pressure values (140/90 mmHg).

Thank you in advance for your help.

Gred