Periodic Body Acceleration Research Articles

Pulsatile flow of blood through a stenosed porous medium under periodic body acceleration

Pulsatile flow of blood through a stenosed porous medium has been studied under the influence of body acceleration. With the help of Laplace and finite Hankel transform, analytical expressions for axial velocity, fluid acceleration, flow rate and shear stress have been obtained. The effect of various parameters entering into the problem is discussed wiht the help of graphs.

Leaback of Pulsatile Flow of Particle Fluid Suspension Model of Blood Under Periodic Body Acceleration

We considered a two-phase model flow of blood subject to both pulsative pressure gradient due to normal heart action and a periodic body acceleration. The leakback of flow due to the fact that the velocity of the red cell is greater than the mean velocity is derived using the method of characteristics. The variation in body acceleration amplitude though affects the velocity profile in the capillary tubes, it has no effect on the leakback in the tubes. Leakback is mainly determined by the balance of the viscous drag and the driving force of the applied pressure gradient. Key words: Leakback, Pulsatile Flow, Fluid Suspension, Periodic Acceleration, Viscous Drag. (Global Journal of Mathematical Sciences: 2002 1 (1&2): 13-16)

The Effects of Periodic Body Acceleration(PGz)Using Noninvasive Motion Ventilation (NIMV), on L-NAME Induced Pulmonary and Systemic Hypertension

The Effects of Periodic Body Acceleration(PGz)Using Noninvasive Motion Ventilation (NIMV), on L-NAME Induced Pulmonary and Systemic Hypertension

Pulsatile flow of particle-fluid suspension model of blood under periodic body acceleration

A particle-fluid suspension model is applied to the problem of pulsatile blood flow through a circular tube under the influence of body acceleration. With the help of finite Hankel and Laplace transforms, analytic expressions for axial velocity for both fluid and particle phase, fluid acceleration, wall shear stress and instantaneous flow rate have been obtained. It is observed that the solutions can be used for all feasible values of pulsatile and body acceleration Reynolds numbers Rp and Rb. Using physiological data, the following qualitative and quantitative results have been obtained. The amplitude Qb of instantaneous flow rate due to body acceleration decreases as the tube radius decreases. The effect of the volume fraction of particle C on Qb is to increase it with increase of C in arteriole and to decrease Qb as C increases in coronary and femoral arteries. The maximum of the axial velocity and fluid acceleration shifts from the axis of the tube to the vicinity of the tube wall as the tube diameter increases. The effect of C on the velocity and acceleration are nonuniform. The wall shear amplitude \(\tau_b\) due to body acceleration increases as the tube diameter decreases from femoral to coronary and a further decrease in the tube diameter leads to a decrease in \(\tau_b\). The effects of C on \(\tau_b\) are again nonuniform.

A mathematical model for the study of the pulsatile flow of blood under an externally imposed body acceleration

The laminar pulsatile flow of blood under the influence of externally imposed body accelerations is studied in the paper. A mathematical model is developed by treating blood as a non-Newtonian fluid, using a biviscosity model for blood. The governing equations are solved by using finite-difference technique. Closed form solutions by Laplace transformations are also obtained for the low pulse frequency region and these solutions are compared with the results obtained numerically and with those of previous studies. Agreement in both the cases is found to be good. Computational results are presented for the effects of periodic body acceleration on the flow of blood passing through a straight cylindrical vessel.

Particulate suspension model for blood flow under external body acceleration

A mathematical model has been developed to investigate the influence of externally imposed periodic body acceleration on blood flow in aorta and arteriole. The rheological properties of blood has been represented by regarding the blood as a two-phase Newtonian fluid, that is, a suspension of cells in plasma. An exact analytical solution of coupled differential equations, describing the flow of a particle-fluid suspension, is obtained using the Laplace transforms technique. The effects of body acceleration and blood cells concentration on velocity, flow rate, acceleration and shear rates are computed and displayed graphically.

Pulsatile flow of third grade fluids under body acceleration—Modelling blood flow

In normal life the human body is quite often subjected to acceleration. Prolonged exposure to such accelerations can generate significant effects on the blood circulation and its rheological behavior depending on the configuration and geometry of the blood vessels. The present study is concerned with a mathematical model for pulsatile blood flow subjected to externally-imposed periodic body acceleration by considering blood as a third grade fluid. The effects of the body acceleration on the velocity, the flow rate and the wall shear stress are estimated numerically through an implicit finite difference scheme for femoral and coronary arteries.

Pulsatile flow of blood with periodic body acceleration

Pulsatile flow of blood through a rigid tube has been studied under the influence of body acceleration. With the help of finite Hankel and Laplace transforms, analytic expressions for axial velocity, fluid acceleration, wall shear and instantaneous volume flow rate have been obtained. It is of interest to note that these solutions can be used for all the feasible values of pulsatile and body acceleration Reynolds numbers Re p and Re b. This is in contrast with the existing results where different approximate solutions have to be used for different ranges of Re p and Re b. Using physiological data, the following qualitative and quantitative results have been obtained. The amplitude of the instantaneous volume flow rate, for flows with body acceleration, decreases shaprly as the tube radius decreases (from aorta to arteriole). This variation of amplitude is very slow for flows with no body acceleration. Another interesting result is the maximum of the axial velocity and fluid acceleration shifts from the tube axis to the vicinity of the tube wall as the tube diameter increases. The variation of the amplitude of wall shear with tube diameter (aorta to coronary) is less for flows with body acceleration than that of flows with no body acceleration. The phase lag between pressure gradient and flow rate changes sharply with tube diameter in narrow tubes, it varies asymptotically in wide tubes. The obtained results are qualitatively in good agreement with existing theoretical observations. Quantitatively, they differ from the other theoretical results (19 to 3000%). The difference in the results of the analyses decreases as the tube diameter increases (arteriole to aorta).

Pulsatile flow of power-law fluid model for blood flow under periodic body acceleration

A mathematical model has been proposed to study the pulsatile flow of a power-law fluid through rigid circular tubes under the influence of a periodic body acceleration. Numerical solutions have been obtained by using finite difference method. The accuracy of the numerical procedure has been checked by comparing the obtained numerical results with other numerical and analytical solutions. It is found that the agreement between them is quite good. Interaction of non-Newtonian nature of fluid with the body acceleration has been investigated by using the physiological data for two particular cases (coronary and femoral arteries). The axial velocity, fluid acceleration, wall shear stress and instantaneous volume flow rate have been computed and their variations with different parameters have been analyzed. The following important observations have been made: (i) The velocity and acceleration profiles can have more than one maxima, this is in contrast with usual parabolic profiles where they have only one maximum at the axis. As n increases, the maxima shift towards the axis; (ii) For the flow with no body acceleration, the amplitude of both, wall shear and flow rate, increases with n, whereas for the flow with body acceleration, the amplitude of wall shear (flow rate) increases (decreases) as n increases; (iii) In the absence of body acceleration, pseudoplastic (dilatant) fluids, with low frequency pulsations, have higher (lower) value of maximum flow rate Qmax than Newtonian fluids, whereas for high frequencies, opposite behavior has been observed; for flow with body acceleration pulsations gives higher (lower) value of Qmax for pseudoplastic (dilatant) fluids than Newtonian fluids.

Casson fluid model for pulsatile flow of blood under periodic body acceleration

Pulsatile flow of a Casson fluid under the influence of a periodic body acceleration has been studied in this paper. An implicit finite difference numerical procedure has been used to analyze the flow. Applicability of this method has been checked by comparing the obtained results with the analytical solution for Newtonian flow and explicit scheme solution. The agreement between the implicit and explicit scheme solutions and the analytical solution is good (error less than 1%). Flow variables have been computed at three locations in cardiovascular system (wide (femoral) and narrow (arteriole and coronary) tubes). Effects of yield stress, tube radius and pressure gradient combined, body acceleration amplitude and frequency etc., on flow have been studied. The following observations have been made: (i) Initial transient time It changes with yield stress in narrow tubes are insignificant, whereas in wide tubes It decreases with yield stress; (ii) The axial velocity and fluid acceleration variations with yield stress are uniform (changes only quantitatively, profiles shape remain same) in narrow tubes, whereas in wide tubes these variations are non-uniform (profiles change qualitatively as well as quantitatively); (iii) Yield stress effects on wall shear amplitude are insignificant in narrow tubes (congruent to 0.3% in arteriole and congruent to 6% in femoral); and (iv) For Newtonian fluid, mean flow rate does not change with body acceleration amplitude a0 and frequency fb but it increases (decreases) with a0(fb) for Casson fluid.

Flow through a stenosed artery subject to periodic body acceleration.

Hjman bodies may occasionally be subjected to high external accelerations. The response of the vascular system under such situations has recently been the subject of several theoretical and experimental studies. However, little work appears to have so far been carried out on the analysis of blood flow in stenosed artery in the presence of body accelerations. In the paper we present a model of blood flow in a partially occluded tube subject to both the pulsatile pressure gradient due to the normal heart action and the periodic body acceleration. Closed-form solutions have been obtained for the instantaneous rate of flow and for the distributions of flow velocity, acceleration and shear stress over the stenosed length. Computational results corresponding to a stenosed carotid artery are presented and discussed.

Analysis of blood flow through a model of the human arterial system under periodic body acceleration

The human system may be subjected to a body acceleration deliberated for example by making subjects lie down on vibrating tables or more frequently unintentionally, for example during travel in water and land or in air and space. The present study is concerned with the effects of externally imposed body accelerations on blood flow in a branched system of arteries. A finite-element model of flow in the arterial system subject to periodic body accelerations is presented. Computational results on the flow rates through selected arteries and the corresponding inlet and outlet pressures under different conditions (magnitude, frequency and direction) of applied acceleration are presented.