ANALYSIS OF DEFORMATION PROCESS OF A BUBBLE IN A CELL MODEL BY SHOCK WAVE FOR DEVELOPING DRUG DELIVERY SYSTEMS

ABSTRACT This paper describes the trial of making microcapsules and deformation analysis of a bubble near the curved elastic wall using macro 2d model and plane shock wave. The prototype microcapsules are made by using micromanipulation systems. It is found that by controlling the initial position of a bubble from the wall and the curvature of the wall there is a point to have large deformation, which tends to be collapsed easily. This is one of the results to aid design of DDS or bioprocess for cell-integration

IMECE2010-40859 SIMULATION OF THROMBUS FORMATION PROCESS USING LATTICE BOLTZMANN METHOD WITH CONSIDERATION OF ADHESION FORCE TO WALL

ABSTRACT Recently artificial organs, especially rotary blood pumps, have been developed in the worldwide, but in this development, thrombus occurs in the pumps. In general, the main physical factors of thrombus formation are considered to be shear rate, wall properties for blood's adhesion. But, there are no proper CFD codes for predicting thrombus formations using physical parameters in shear flows. In this paper, new model for predicting thrombus formation by considering aggregation and adhesion force to the wall by lattice Boltzmann method is proposed, and the trend of thrombus's adhesion to the wall can be simulated more adequately than that of previous one. INTRODUCTION To suppress the hemolysis (red blood cell damage) and avoid the thrombus is very important problem in developing the rotary blood pumps and heart valves. In spite of complicacy of thrombus formation phenomena, it is preferable for mechanical engineer to design the devices using the simple prediction tool such as CFD software. In general, thrombus phenomenon is multi scale process from micro scale to macro scale. Usually finite difference method (FDM) is used for these multiphase flows, but FDM needs strict parameters for solving governing equations and huge computational cost. Comparing with FDM, the lattice Boltzmann method (LBM) [1] is powerful tool because of its simple algorithm for these multi scale problems

Computational fluid dynamics study of the aortic valve opening on hemodynamics characteristics

In this work, the 3D geometry of patient specific aorta was utilized to carry out CFD studies on the effect of different valve opening (45°,62.5° and fully opening) on the hemodynamic properties. The result shows that the lower valve opening induced jet flow and hampered the flow on the additional carotid arteries. Besides, the leaflets were subjected to extreme stress values having disastrous consequences. Consequently, stenosis which is characterized by weaker leaflets and low valve openings has serious impact on the well being of humans

Numerical analysis using a fixed grid method for cardiovascular flow application

Motivated by the current interest in the numerical simulation of biological flows in the human body, we develop a new method to simulate fluid flow embedded in a solid region. The novelty of this method lies on the use of a fixed grid in the entire computational domain. The formulation is an extension of the multiphase fluid flow that belongs to the category of the penalty method, where high viscosity is imposed on a solid region. A free open source library, namely, OpenFOAM, is used to integrate high order and advanced numerical schemes into these computational formulations. The Monotone Upstream System for Conservation Laws (MUSCL) scheme by van Leer, with a harmonic limiter from the category of the total variation bounded (TVB) scheme, is used for cell face interpolation. The robustness and accuracy of the solver are compared with the benchmark test case, namely, the free fall of a solid sphere. The test case validates that the rigidity of the solid sphere is ensured with the selected high viscosity ratio. The accurate terminal velocity of the falling solid sphere proves the no-slip condition at the solid-liquid interface. As a real application implementation, the flow on a simplified idealized model of heart valve stenosis is presented

Computational fluid dynamics study of blood flow in aorta using OpenFOAM

Understanding of flow pattern behaviour inside the aorta contributes significantly in diseases treatment artificial design. Objective of present study is to simulate the blood flow in patient specific aorta using open source computational fluid dynamics (CFD) platform OpenFOAM. The real geometry was obtained from real male Malaysian patient. There are not much data available in literature incorporate real geometry of aorta due to complex geometry. The validation is done against existing experimental result of the 90 degree curve tube model. It was shown that our method is able to capture complex flow in the curve tube like secondary and separation flow that responsible for development of wall shear stress at the tube wall. These flow physics could have similarity in aorta blood flow. Finally, we apply our method with anatomy human aorta with pulsatile inlet condition. Further comparison is made with unstructured boundary fitted mesh. The final result shows that the detailed flow physics can be captured in an aorta

Computational Fluid Dynamics Study Of Blood Flow In Aorta Using OpenFOAM

Understanding of flow pattern behaviour inside the aorta contributes significantly in diseases treatment artificial design.Objective of present study is to simulate the blood flow in patient specific aorta using open source computational fluid dynamics (CFD) platform OpenFOAM.The real geometry was obtained from real male Malaysian patient.There are not much data available in literature incorporate real geometry of aorta due to complex geometry.The validation is done against existing experimental result of the 90 degree curve tube model.It was shown that our method is able to capture complex flow in the curve tube like secondary and separation flow that responsible for development of wall shear stress at the tube wall.These flow physics could have similarity in aorta blood flow.Finally,we apply our method with anatomy human aorta with pulsatile inlet condition.Further comparison is made with unstructured boundary fitted mesh.The final result shows that the detailed flow physics can be captured in an aorta

Review of numerical methods for simulation of mechanical heart valves and the potential for blood clotting

Even though the mechanical heart valve (MHV) has been used routinely in clinical practice for over 60 years, the occurrence of serious complications such as blood clotting remains to be elucidated. This paper reviews the progress that has been made over the years in terms of numerical simulation method and the contribution of abnormal flow toward blood clotting from MHVs in the aortic position. It is believed that this review would likely be of interest to some readers in various disciplines, such as engineers, scientists, mathematicians and surgeons, to understand the phenomenon of blood clotting in MHVs through computational fluid dynamics

The hemodynamic effects of paravalvular leakage using fluid structure interaction; transcatheter aortic valve implantation patient

In this study, the fluid structure interaction (FSI) method was utilized to investigate the hemodynamic effects between normal aorta and aorta with Transcatheter Aortic Valve Implantation (TAVI) of paravalvular leakage (PVL). A 3D model of patient specific aorta with annulus diameter of 27.3 mm was developed using MIMICS software. In this research, a similar TAVI valve model by referring to SXT 26 Edwards SAPIENT valve was drawn using CATIA software with valve opening of 100%. The two way of fluid structure interaction analysis has been performed using ANSYS 14.5 software (ANSYS Inc. Canonsburg, PA, USA). The results revealed that the undersized TAVI valve lead to PVL. It was noticed that the PVL happened at the gap in-between the TAVI valve and annulus diameter which is not completely round in shape. This phenomenon produced recirculation flow at the right side of ascending aorta after the flow passing through the valve. It has been proven that the PVL caused a huge impact on the losses of the mass flow rate and also recirculation of blood flow which may lead to blood thrombosis. Furthermore, the data shows that PVL causes higher aortic wall deformation instead of normal aortic condition and may lead to migration of the valve. Consequently, PVL may cause other serious problems such as stroke, arrhythmias and coronary ischemia, which required reoperation

FEDSM2008-55320 DEVELOPMENT OF MICROCAPSULES INCLUDING A GAS BUBBLE FOR SHOCK WAVE BASED DRUG DELIVERY

ABSTRACT This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems, evaluation of their mechanical properties and development of new driving mechanics of the microcapsules. INTRODUCTION Shock wave is a discontinuous wave that has high maximum pressure and short rise time. It is expected to apply this shock wave to another research field. We have proposed drug delivery systems (DDS) using shock waves in order to apply micro/nano technology in the fields of biomedical engineering. In this system, a microcapsule including a gas bubble is flown in the blood vessel, and finally broken by shock induced microjet, then drug is reached to the affected part in the body as same as traditional DDS. This method is efficient way to transfer the drugs near the affected part in human body, because there are no thermal effects on the living tissue by using shock wave comparing with the ultrasonic method. For developing microcapsules including a gas bubble, the penetration force of microjet should be controlled by shock wave strength (power), wave form of pressure, and capsule geometry and material properties. Especially the mechanical properties of membrane and geometry of the membrane is important parameter for changing the penetration strength of microjet in the microcapsule. But the relation of the penetration strength of microjet and the membrane thickness and elasticity is not clear even in the research field of bubble dynamics. It is difficult t

IMECE2008-67265 CFD BASED PREDICTION METHOD OF THROMBUS FORMATION IN SHEAR FLOW AND ITS VALIDATION

ABSTRACT This paper describes development of the prediction method of thrombus formation by Computational Fluid Dynamics (CFD) on pipe orifice shear flows. These shear flows are typical models of the flow in the rotary blood pump. In this investigation, the thrombus formation in blood plasma flow is visualized, and modified lattice Boltzmann method are used to predict the backward forwarding step flow, that is simple model of the orifice flow. INTRODUCTION Recently artificial organs, especially rotary blood pumps, have been developed in the worldwide, but in this development, hemolysis (red blood cell damage by shear stress) and thrombus occur in the pumps. To suppress the hemolysis and avoid the thrombus is very important and serious problem in developing the rotary blood pumps. In case of developing the artificial heart valve and stent, there are also same problems. As for thrombus formation, it is very important to predict it for designing the medical fluidics with blood flows. Compared with hemolysis, the mechanism of thrombus formation is much complicated because it includes biochemical factors. In spite of this complicacy, it is preferable for mechanical designer to design simply using the some thresholds of physical factors. The main physical factors of thrombus formation are shear stress (shear rate), wall properties for blood's adhesion and transport process of aggregation factor in the flow. In this study, the thrombus formation in the blood plasma flow is visualized, and the modified lattice boltzmann method are used to predict the backward forwarding step flow