A simple and highly accurate semi-analytical method, called the differential transformation method(DTM), was used for solving the nonlinear temperature distribution equation in solid and porous longitudinal fin with t...A simple and highly accurate semi-analytical method, called the differential transformation method(DTM), was used for solving the nonlinear temperature distribution equation in solid and porous longitudinal fin with temperature dependent internal heat generation. The problem was solved for two main cases. In the first case, heat generation was assumed variable by fin temperature for a solid fin and in second heat generation varied with temperature for a porous fin. Results are presented for the temperature distribution for a range of values of parameters appearing in the mathematical formulation(e.g. N, εG, and G). Results reveal that DTM is very effective and convenient. Also, it is found that this method can achieve more suitable results in comparison to numerical methods.展开更多
The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparis...The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparison between OHAM and numerical method shows that OHAM is an exact and high efficient method for solving these kinds of problems. The results are presented to study the velocity and rotation profiles for different physical parameters such as Reynolds number, vortex viscosity parameter, spin gradient viscosity and microinertia density parameter. As an important outcome, the magnitude of the microrotation increases with an increase in the values of injection velocity while it decreases by increasing the values of suction velocity.展开更多
Electrospinning is a useful and efficient technique to produce polymeric nanofibers. Nanofibers of polymers are electrospun by creating an electrically charged jet of polymer solution. Numerical study on non-Newtonian...Electrospinning is a useful and efficient technique to produce polymeric nanofibers. Nanofibers of polymers are electrospun by creating an electrically charged jet of polymer solution. Numerical study on non-Newtonian and viscoelastic jets of polymer nanofibers in electrospinning process is presented in this work. In particular, the effect of non-Newtonian rheology on the jet profile during the electrospinning process is examined. The governing equations of the problem are solved numerically using the Keller-Box method. The effects of yield stress and power-law index on the elongation, velocity, stress and total force are presented and discussed in detail. The results show that by increasing the values of yield stress, the fluid elongation is reduced significantly.展开更多
‘Stent versus stent＇ studies are a kind of randomized trials which are designed to show the superiority of the new stent designs compared with the previously approved ones. These studies are usually used by regulato...‘Stent versus stent＇ studies are a kind of randomized trials which are designed to show the superiority of the new stent designs compared with the previously approved ones. These studies are usually used by regulatory agencies, such as the U.S. Food and Drug Administration （FDA）, to give an approval to new stent designs. The problem with these clinical trials is their high cost and difficulty. In this paper, a numerical alternative for ＇stent versus stent＇ complicated clinical studies is presented. A finite element model is developed to investigate the influence of stent design on the outcome after coronary stent placement. Two commercially available stents （the NIR and Multi-Link stents） are modeled and their behavior during the deployment is compared in terms of stress distribution, radial gain, outer diameter changes and foreshortening. Moreover, the effect of stent design on the restenosis rate is investigated by comparing the stress distribution within the arteries. An analysis of the arterial wall stresses in the stented arteries indicates that the Multi-Link stent design causes lower stress to an atherosclerotic vessel with a localized stenotic lesion compared to the slotted tube NIR design. The findings correlate with the observed clinical restenosis rates, which have reported higher restenosis rates in the NIR compared with the Multi- Link stent design.展开更多
In the present paper a differential transformation method(DTM)is used to obtain the solution of momentum and heat transfer equations of non-Newtonian fluid flow in an axisymmetric channel with porous wall.The comparis...In the present paper a differential transformation method(DTM)is used to obtain the solution of momentum and heat transfer equations of non-Newtonian fluid flow in an axisymmetric channel with porous wall.The comparison between the results from the differential transfomiation method and numerical method are in well agreement which proofs the capability of this method for solving such problems.After this validity,results are investigated for the velocity and temperature for various values of Reynolds number,Prandtl number and power law index.展开更多
文摘A simple and highly accurate semi-analytical method, called the differential transformation method(DTM), was used for solving the nonlinear temperature distribution equation in solid and porous longitudinal fin with temperature dependent internal heat generation. The problem was solved for two main cases. In the first case, heat generation was assumed variable by fin temperature for a solid fin and in second heat generation varied with temperature for a porous fin. Results are presented for the temperature distribution for a range of values of parameters appearing in the mathematical formulation(e.g. N, εG, and G). Results reveal that DTM is very effective and convenient. Also, it is found that this method can achieve more suitable results in comparison to numerical methods.
文摘The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparison between OHAM and numerical method shows that OHAM is an exact and high efficient method for solving these kinds of problems. The results are presented to study the velocity and rotation profiles for different physical parameters such as Reynolds number, vortex viscosity parameter, spin gradient viscosity and microinertia density parameter. As an important outcome, the magnitude of the microrotation increases with an increase in the values of injection velocity while it decreases by increasing the values of suction velocity.
文摘Electrospinning is a useful and efficient technique to produce polymeric nanofibers. Nanofibers of polymers are electrospun by creating an electrically charged jet of polymer solution. Numerical study on non-Newtonian and viscoelastic jets of polymer nanofibers in electrospinning process is presented in this work. In particular, the effect of non-Newtonian rheology on the jet profile during the electrospinning process is examined. The governing equations of the problem are solved numerically using the Keller-Box method. The effects of yield stress and power-law index on the elongation, velocity, stress and total force are presented and discussed in detail. The results show that by increasing the values of yield stress, the fluid elongation is reduced significantly.
文摘‘Stent versus stent＇ studies are a kind of randomized trials which are designed to show the superiority of the new stent designs compared with the previously approved ones. These studies are usually used by regulatory agencies, such as the U.S. Food and Drug Administration （FDA）, to give an approval to new stent designs. The problem with these clinical trials is their high cost and difficulty. In this paper, a numerical alternative for ＇stent versus stent＇ complicated clinical studies is presented. A finite element model is developed to investigate the influence of stent design on the outcome after coronary stent placement. Two commercially available stents （the NIR and Multi-Link stents） are modeled and their behavior during the deployment is compared in terms of stress distribution, radial gain, outer diameter changes and foreshortening. Moreover, the effect of stent design on the restenosis rate is investigated by comparing the stress distribution within the arteries. An analysis of the arterial wall stresses in the stented arteries indicates that the Multi-Link stent design causes lower stress to an atherosclerotic vessel with a localized stenotic lesion compared to the slotted tube NIR design. The findings correlate with the observed clinical restenosis rates, which have reported higher restenosis rates in the NIR compared with the Multi- Link stent design.
文摘In the present paper a differential transformation method(DTM)is used to obtain the solution of momentum and heat transfer equations of non-Newtonian fluid flow in an axisymmetric channel with porous wall.The comparison between the results from the differential transfomiation method and numerical method are in well agreement which proofs the capability of this method for solving such problems.After this validity,results are investigated for the velocity and temperature for various values of Reynolds number,Prandtl number and power law index.
