The gravitational effects of blood flow in irregular stenosed artery with various severity / Yan BinTan and Norzieha Mustapha

The mathematical study investigates the influences of gravitational force in an artery segment onthe various severity of the stenosis. Blood flow along the arterial segment is considered as incompressible Newtonian fluid. An unsteady two-dimensional nonlinear model is taken where the governing Navier-Stokes equations are added with significant gravity term. Marker and Cell (MAC) method based on finite difference approximations in a staggered grid is selected to solve the problem. Results obtained show that slight difference of areal occlusion percentage of severe stenosis in a vessel can lead to significant impacts on blood flow patterns. With the presence of the gravitational acceleration force, the pressure and axial velocity along the vessel is generally higher than without the gravitational force. Besides, the wall shear stress is lowerand therecirculation region is smallerin the presence of gravitational forc

A numerical simulation and visualization of blood flow through a stenosed artery with the different severity

The cardiovascular system consist of the heart and blood vessels that carrying blood in whole human bodies. The heart is a vital organ in the human body. The heart disease is the most common chronic disease of the coronary arteries is called atherosclerosis. Atherosclerosis occurs when a build-up of plaque or cholesterol deposits on artery walls. Over time, plaque can accumulate, harden and narrow the arteries and impede blood flow to the heart. Coronary artery disease or coronary artery disease (CAD) is the basically can caused heart attacks, strokes, various heart disease including congestive heart failure and most cardiovascular disease in general. A blockage in one or more coronary arteries can cause heart attack suddenly. In addition, diseased arteries also tend to experience sudden muscle contractions. Thus, a piece of a blood crust can form a contraction, release chemicals which then result in narrowing the artery wall, triggering a heart attack. If the working system of the heart is damage, the normal rhythm of the heart can become chaotic and the heart began to tremble with uncertainty or experiencing fibrillation. This abnormal rhythm known as arrhythmia is a deviation from the normal heart rhythm. This will cause the heart’s ability to pump blood effectively to the brain

Partial slip effect on heat and mass transfer of MHD peristaltic transport in a porous medium

This research looks at the effects of partial slip on heat and mass transfer of peristaltic transport. The magnetohydrodynamic (MHD) flow of viscous fluid in a porous asymmetric channel has been considered. The exact solutions for the stream function, longitudinal pressure gradient, longitudinal velocity, shear stress, temperature and concentration fields are derived by adopting long wavelength and small Reynolds number approximations. The results showed that peristaltic pumping and trapping are reduced with increasing velocity slip parameter. Furthermore, temperature increases with increasing thermal slip parameter. Moreover, the concentration profile decreases with increasing porosity parameter, Schmidt number and concentration slip parameter. Comparisons with published results are found to be in good agreement

New exact solutions of stokes' second problem for an MHD second grade fluid in a porous space

We investigate a problem describing the oscillating flow of an incompressible magnetohydrodynamic (MHD) second grade fluid in a porous half space. Exact solutions for sine and cosine oscillations are developed by applying the Laplace transform method. The total obtained solution is a sum of steady and transient solutions. Particular attention is given to the effects of magnetic and porous medium parameters on the velocity. It is shown that previous results for a non-porous medium and hydrodynamic fluid are the limiting cases of the present problem. The results for velocity are plotted and discussed carefully

Unsteady magnetohydrodynamic oscillatory flow of viscoelastic fluids in a porous channel with heat and mass transfer

In this paper, we analyze the effects of slip condition on the unsteady magnetohydrodynamic (MHD) flow of incompressible viscoelastic fluids in a porous channel under the influence of transverse magnetic field and Hall current with heat and mass transfer. The channel flow is induced due to external pressure gradient of oscillatory form. The governing equations for the velocity field, temperature and concentration distributions, are solved using perturbation technique. We present the results for skin friction, Nusselt number and Sherwood number. The numerical results are also computed for skin friction in tabular form. The effects of various indispensable flow parameters are displayed using several graphs. The numerical results show the effects of the physical parameters on the fluid flow as well as on heat and mass transfer and skin friction. The solutions for Newtonian fluids can be obtained as a limiting case from our general solutions when the viscoelastic parameter is zero. © 2012 The Physical Society of Japan

Closed-form solutions for accelerated MHD flow of a generalized Burgers’ fluid in a rotating frame and porous medium

Closed-form solutions for magnetohydrodynamic (MHD) and rotating flow of generalized Burgers’ fluid past an accelerated plate embedded in a porous medium are obtained using the Laplace transform technique. Modified Darcy’s law for generalized Burgers’ fluid is taken into account. Both constant and variable acceleration cases are considered. The graphical results along with illustrations are presented to bring out the effects of indispensable parameters on the velocity. The obtained solutions are reduced as special cases to their limiting solutions by taking some suitable parameters equal to zero

The unsteady power law blood flow through a multiirregular stenosed artery

A non-Newtonian pulsatile model of blood flow through multiple stenoses with irregular surfaces is considered. The model chosen is the generalized power law model of blood viscocity where the flow is assumed to be unsteady, laminar, two dimensional and axisymmetric. The governing equations of motion in terms of the viscous shear stress and the boundary conditions in the cylindrical coordinate system are first transformed using a radial coordinate transformation before they are discretized using a finite difference scheme based on central difference approximations on non-uniform grids. The numerical results obtained in terms of blood flow characterictics show that the values of the axial velocity and flow rate in the power-law model are lower while the resistance to flow and the wall shear stress are higher compared to the Newtonian model. These features concur with the general observations of blood flowing through small stenosed arteries

Numerical modelling and simulation of blood flow through a multi-irregular stenosed artery

The blood flow problem in a multi-irregular stenosed artery is important from the physiological considerations in view of many clinical situations. For instance, the patient is found to have multiple stenoses in the same arterial segment and the geometry of the stenosis is irregular. In this study, numerical modelling of blood flow through a multi-irregular stenosed artery is developed. Experimental investigations have also revealed that blood exhibits non-Newtonian properties at low shear rate. This research deals with both Newtonian and non-Newtonian models of blood flow. Such effects have been studied in the form of generalized Newtonian fluid, where apparent viscosity decreases by increasing shear rate. Two external factors namely periodic body acceleration and magnetic field have been considered. Numerical solutions are established under the assumptions that the flow is axisymmetric, unsteady, laminar, fully developed and two-dimensional. Numerical computation by finite difference Marker and Cell (MAC) method has been used to discretize the governing equations of motion for unsteady flow in the cylindrical polar co-ordinate system. The obtained pressure-Poisson equation was then solved through the successive-over-relaxation (S.O.R.) method. The obtained numerical results show good agreement with the experiments. It is found that under the influence of body acceleration, the velocity and flow rate are increased. The pressure drop gives higher values and the separation region is found to be larger in the case of blood flowing through a flexible artery having multiple irregular stenoses when compared to blood flowing through a single irregular stenosed artery. Furthermore, when magnetic field is increased, the velocity gradient near the wall and the wall shear stress will also be increased. With a sufficiently large magnetic field, the flow separations completely disappeared. The generalized Newtonian model results in a higher pressure drop with a smaller separation region in comparison to the Newtonian fluid

Heat transfer on peristaltic flow of fourth grade fluid in inclined asymmetric channel with partial slip

In this paper, the effects of slip and heat transfer are studied on the peristaltic transport of a magnetohydrodynamic (MHD) fourth grade fluid. The governing equations are modeled and solved under the long wavelength approximation by using a regular perturbation method. Explicit expressions of solutions for the stream function, the velocity, the pressure gradient, the temperature, and the heat transfer coefficient are presented. Pumping and trapping phenomena are analyzed for increasing the slip parameter. Further, the temperature profiles and the heat transfer coefficient are observed for various increasing parameters. It is found that these parameters considerably affect the considered flow characteristics. Comparisons with published results for the no-slip case are found in close agreement