SUBJECT: Ph.D. Dissertation Defense
BY: Brian Yun
TIME: Wednesday, November 13, 2013, 1:00 p.m.
PLACE: College of Computing Building, 053
TITLE: Simulations of Pulsatile Flow through Bileaflet Mechanical Heart Valves Using a Suspension Flow Model: To Assess Blood Damage
COMMITTEE: Dr. Ajit P. Yoganathan, Co-Chair (BME)
Dr. Cyrus K. Aidun, Co-Chair (ME)
Dr. G. Paul Neitzel (ME)
Dr. Don P. Giddens (BME)
Dr. W. Robert Taylor (BME)


Native heart valves serve an important function in maintaining unidirectional flow of blood through the heart. Defective or diseased native valves have been replaced by prosthetic heart valves for several decades with improved performance and patient conditions. However, severe complications such as hemolysis and unwanted thrombosis still exist due to the presence of the prostheses. A popular example of a prosthetic device is the bileaflet mechanical heart valve (BMHV). Modern BMHV designs have undergone significant evolution and are frequently chosen due to good hemodynamics performance and long durability. However, blood element trauma and thromboembolic events still remain, leading to lifelong dependence on anticoagulants. These problems have been linked to blood damage caused by non-physiological stresses due to complex flow fields that arise from prosthetic valve design. In order to reduce the severity of complications, blood damage that occurs in prosthetic heart valve flows must be well understood. The aim of this research is to numerically study platelet damage that occurs in flow through bileaflet mechanical heart valves. The numerical suspension flow simulations use a fluid-solid coupling method that combines lattice-Boltzmann fluid modeling with the external boundary force method. This method is first validated as a general suspension flow solver, then for parallel modeling performance. The flow modeling method is then validated against experimental data of pulsatile, high Reynolds number BMHV flows. Blood damage is then evaluated for a baseline physiologic adult case of BMHV flow and results are analyzed in a variety of viewpoints. This method can be used as a generic tool for future evaluation of novel prosthetic devices or cardiovascular flow problems. Using accurate blood element damage modeling, the numerical method can help to understand cardiovascular blood flow complications in ways that other experimental and computational methods cannot.