Hartmann number

About: Hartmann number is a research topic. Over the lifetime, 2593 publications have been published within this topic receiving 61342 citations.

Effects of magnetic field, porosity, and wall properties for anisotropically elastic multi-stenosis arteries on blood flow characteristics

Abstract: A mathematical model for blood flow through an elastic artery with multistenosis under the effect of a magnetic field in a porous medium is presented The considered arterial segment is simulated by an anisotropically elastic cylindrical tube filled with a viscous incompressible electrically conducting fluid representing blood An artery with mild local narrowing in its lumen forming a stenosis is analyzed The effects of arterial wall parameters represent viscoelastic stresses along the longitudinal and circumferential directions T t and T θ , respectively The degree of anisotropy of the vessel wall γ, total mass of the vessel, and surrounding tissues M and contributions of the viscous and elastic constraints to the total tethering C and K respectively on resistance impedance, wall shear stress distribution, and radial and axial velocities are illustrated Also, the effects of the stenosis shape m, the constant of permeability X, the Hartmann number H α and the maximum height of the stenosis size δ on the fluid flow characteristics are investigated The results show that the flow is appreciably influenced by surrounding connective tissues of the arterial wall motion, and the degree of anisotropy of the vessel wall plays an important role in determining the material of the artery Further, the wall shear stress distribution increases with increasing T t and γ while decreases with increasing T θ , M, C, and K Transmission of the wall shear stress distribution and resistance impedance at the wall surface through a tethered tube are substantially lower than those through a free tube, while the shearing stress distribution at the stenosis throat has inverse characteristic through totally tethered and free tubes The trapping bolus increases in size toward the line center of the tube as the permeability constant X increases and decreases with the Hartmann number Ha increased Finally, the trapping bolus appears, gradually in the case of non-symmetric stenosis, and disappears in the case of symmetric stenosis The size of trapped bolus for the stream lines in a free isotropic tube (ie, a tube initially unstressed) is smaller than those in a tethered tube

Entropy generation of MHD nanofluid inside an inclined wavy cavity by lattice Boltzmann method

Abstract: In this study, lattice Boltzmann method is applied in order to simulate the magnetohydrodynamic (MHD) natural convection heat transfer and entropy generation of CuO–water nanofluid inside an inclined wavy cavity. The left wavy wall is heated sinusoidal, while the right flat wall is kept at a constant temperature. The top and the bottom horizontal walls are smooth and insulated against heat and mass. The effects of active parameters such as solid volume fraction of nanoparticles, Rayleigh number, Hartmann number and inclination angles are examined on flow, heat transfer and entropy generation. The results proved that the heat transfer and entropy generation decline significantly with increasing Hartmann numbers, while those rise with increasing Rayleigh numbers. The results show that the effect of nanoparticles volume fraction on dimensionless Nusselt number and entropy generation is more pronounced at high Rayleigh number than at low Rayleigh number. Also the results indicate that the mean Nusselt number and total entropy generation changes with inclination angle, while the minimum values of $$Nu_{\text{m}}$$ and S belong to $$\theta = \pi /3$$ and 0, respectively.

Hall effects on MHD natural convection flow in a vertical microchannel

Abstract: In this work, the steady fully developed magnetohydrodynamic natural convection flow in a vertical microchannel formed by two infinite vertical parallel plates due to asymmetric heating of parallel plates in the presence of Hall current is studied. Effects of velocity slip and temperature jump have been considered on the microchannel surfaces and exact solutions have been obtained for momentum and energy equations under relevant boundary conditions. The influence of each governing parameter such as Hall current parameter, Hartmann number, rarefaction parameter, fluid wall interaction parameter and wall-ambient temperature ratio on flow formation is discussed with the aid of graphs. The significant result from the study is that, increase in the value of rarefaction parameter leads to enhancement in volume flow rate. Furthermore, it is evident that volume flow rate is found to be increasing function of Hall current parameter.

Effects of transverse magnetic field with variable thermal conductivity on tangent hyperbolic fluid with exponentially varying viscosity

Abstract: The purpose of present analysis is to examine the effects of temperature dependent viscosity and thermal conductivity on MHD stagnation point flow over a stretching cylinder. The momentum and the temperature equations are modeled by using tangent hyperbolic fluid and the effect of viscous dissipation is also considered. The requisite partial differential equations are metamorphosed into ordinary differential equations by using similarity transformations. The succeeding ordinary differential equations are solved by using shooting method. The physical behavior of non-dimensional parameters for momentum and temperature profiles is deliberated through graphs. The numerical values of skin friction coefficient and local Nusselt number are calculated in order to recognize the behavior of fluid near the surface. The comparison with previous literature is completed in order to check the accuracy of the present work. It is found the velocity reduces with increasing power law index, Weissenberg number, Hartmann number and variable viscosity parameter. With the increasing values of curvature parameter, velocity is found to increase. Variable thermal conductivity parameter and Prandtl number shows opposite behavior for temperature profile.