Hello SimVascular community,
I have a question regarding the assignment of boundary conditions in SimVascular. After reading through the forum, I noticed it's generally not recommended to prescribe flow rates at the outlets. I wanted to verify my understanding and would appreciate any feedback.
In many hemodynamic simulations, setting flow rates for both the inlet and outlets can be problematic because the flow must balance with the internal pressure distribution. This could result in inconsistencies or unrealistic simulations. Since blood flow in vascular systems is typically pressure-driven, it depends on pressure gradients across the system. Fixing both inlet and outlet flow rates might prevent capturing a realistic pressure distribution, particularly at the outlets.
Could someone confirm if my interpretation is correct?
Thank you,
Melton
Clarification on Boundary Conditions in SimVascular
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Melton Parham
- Posts: 4
- Joined: Sun Dec 10, 2023 3:16 pm
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Evangelos Stamos
- Posts: 5
- Joined: Thu Oct 19, 2023 10:10 am
Re: Clarification on Boundary Conditions in SimVascular
Hi Melton,
You are correct in your understanding that prescribing flow rates at both the inlet and outlets in hemodynamic simulations can lead to issues, especially regarding pressure distribution. In cardiovascular systems, blood flow is indeed primarily pressure-driven, and the pressure gradient across the vessels governs the flow.
Setting flow rates at the outlets can introduce artificial constraints that don't align with the real physiological behavior, where flow adapts dynamically to the pressure distribution in response to resistance from the downstream vasculature. When both inlet and outlet flow rates are fixed, the simulation may fail to capture this dynamic, leading to an unbalanced or unrealistic solution.
Instead, many simulations use boundary conditions like zero-pressure, resistance, or Windkessel models at the outlets to better approximate the interaction between the vascular system and the surrounding tissues or downstream vessels. These methods allow the simulation to balance flow naturally based on pressure, more accurately reflecting physiological conditions.
Your interpretation is aligned with standard practices, and it's generally recommended to avoid prescribing flow rates at the outlets unless you have a very specific reason to do so.
Best regards,
Evangelos.
You are correct in your understanding that prescribing flow rates at both the inlet and outlets in hemodynamic simulations can lead to issues, especially regarding pressure distribution. In cardiovascular systems, blood flow is indeed primarily pressure-driven, and the pressure gradient across the vessels governs the flow.
Setting flow rates at the outlets can introduce artificial constraints that don't align with the real physiological behavior, where flow adapts dynamically to the pressure distribution in response to resistance from the downstream vasculature. When both inlet and outlet flow rates are fixed, the simulation may fail to capture this dynamic, leading to an unbalanced or unrealistic solution.
Instead, many simulations use boundary conditions like zero-pressure, resistance, or Windkessel models at the outlets to better approximate the interaction between the vascular system and the surrounding tissues or downstream vessels. These methods allow the simulation to balance flow naturally based on pressure, more accurately reflecting physiological conditions.
Your interpretation is aligned with standard practices, and it's generally recommended to avoid prescribing flow rates at the outlets unless you have a very specific reason to do so.
Best regards,
Evangelos.