One of the initiative’s first, and most valuable, products is the SIMULIA Living Heart Human Model, a dynamic, anatomically detailed, finite-element (FE) model, representing the electrical and physical behavior of a four-chamber heart, with a simplified fluid (blood) model capable of representing dynamic pressure/volume changes in intra- and extra-cardiac circulation.
To fully understand cardiac function, it’s necessary to go beyond modeling the structure of the heart, and look at the detailed behavior of blood (i.e. cardiac hemodynamics) as it interacts with that structure. This can be accomplished by using a technology borrowed from aerospace and automotive engineering: Computational Fluid Dynamics (CFD) simulation. Though not without some significant challenges:
- The heart structure enclosing the fluid (blood) volume is geometrically very complex.
- Heart beats cause large and rapid deformations of the fluid volume. (i.e., fluid-structure interactions.)
- Variations in fluid pressure cause deformations in the heart valves. (Also fluid-structure interactions.)
- Complex and time-varying patterns of extra-cardiac circulation make the defining boundary conditions (inflows and outflows) difficult.
- Motions of tissue and mechanical valves are and their contact interfaces with heart tissue boundaries are difficult to accurately model.
In the past, the difficulty in dealing with these challenges has effectively limited the use of CFD for cardiac hemodynamics, only allowing oversimplified approaches and requiring the involvement of simulation experts.
Recent cooperative work by Living Heart Project members Capvidia and Dassault Systemes SIMULIA Corporation has led to a methodology that addresses these challenges, through bidirectional coupled simulation using the general purpose CFD code FlowVision and the SIMULIA Living Heart Human Model.
There are two significant factors in particular that distinguish this methodology from older practices:
- While most CFD codes are optimized to model fluid domains using tetrahedral or hexahedral meshes (which, for non-trivial cases, must be constructed manually), FlowVision is optimized to work with automatically generated computational grids, created using the sub-grid geometry resolution (SGGR™) method. Because of this, FlowVision is able to dynamically reconstruct the fluid domain as the heart structure deforms during the heartbeat process, with no need for manual intervention.
- FlowVision and SIMULIA both include tools for managing coupled simulations, and ensuring accurate and automatic mapping between the models of the fluid domain and heart structure, accounting for bidirectional fluid-structure interactions.
Ultimately, the greatest benefit of this methodology is that it enables more sophisticated and realistic cardiac simulations, while simultaneously lowering the barrier to entry for researchers who are not experts in simulation.
Human HeartCapvidia is a sponsor of the Age of Experience conference, May 16-18, 2017, in Chicago, where it will present a paper on the methodology titled Coupled Multi-Physics Simulation of Blood Flow and Tissue Mechanics in Living Human Heart Model.
FlowVision is a product of Capvidia, a developer of software for simulation, CAD data translation/validation, reverse-engineering, and model-based definition.
For more information about the Living Heart Project:
About the SIMULIA Living Heart Human Model
The SIMULIA Living Heart Human Model is a product of Dassault Systemes, developed as part of the Living Heart Project.