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Foolad Shahr, Iran

Monfared M.,Isfahan University of Technology | Shirani E.,Foolad Institute of Technology | Salimpour M.R.,Isfahan University of Technology | Aloui F.,University of Lille Nord de France
Acta Mechanica

In this research, experimental and numerical techniques are used to study the flow history effects of axial flow on the Couette–Taylor flow. For the experimental investigation, the flow is visualized using the PIV technique with reflective particles with a density of 1.62 g/cm3. Dispersed in a solution, the particles have a strong refraction index equal to 1.85. In this study, two protocols are adopted to study the effect of an axial flow superimposed on a Couette–Taylor flow, and of the history of the flow. The first one, the direct protocol, consists of imposing an azimuthal flow to the inner cylinder. In this case, when the regime is established, the axial flow is superimposed. The second protocol, the inverse protocol, consists of imposing first the axial flow in the gap of the system, after which an azimuthal flow is conveyed. The Couette–Taylor flow with axial flow is strongly dependent on the flow history (the protocol). Thus, the flow structures and development for different protocols are studied and analyzed here experimentally and numerically. In addition, from the numerical results, mathematical models for the two protocols are presented. For the direct protocol, a new relation between the axial Reynolds number, which stabilizes the Couette–Taylor flow, and the Taylor number is presented; for the inverse protocol, a new mathematical model for the critical Taylor number is developed as a function of the axial Reynolds number and also the first critical Taylor number without axial flow. © 2016 Springer-Verlag Wien Source

Alavi S.,Foolad Institute of Technology
International Journal of Technological Learning, Innovation and Development

A lack of workforce agility has been reported as one of the main reasons that some enterprises have difficulty keeping pace with markets and technological changes. Shortage of research on the consequences of workforce agility can be one of the main reasons for inconsideration about workforce agility in SMEs. In order to contribute to this debate, this research investigates whether and how extent workforce agility is a critical factor for promoting external manufacturing flexibility, as a key component in dynamic environment. The study is conducted by gathering sample from 161 Iranian SMEs. Supporting the hypotheses, the results suggest workforce agility enhances new product, mix, and volume flexibility. Moreover, testing the relationship between external manufacturing flexibility dimensions shows that mix flexibility encourages volume and new product flexibility in the SMEs. © Copyright 2016 Inderscience Enterprises Ltd. Source

Sayed Razavi M.,Isfahan University of Technology | Shirani E.,Foolad Institute of Technology
Journal of Biomechanics

In the present study, theoretical formulations for calculation of optimal bifurcation angle and relationship between the diameters of mother and daughter vessels using the power law model for non-Newtonian fluids are developed. The method is based on the distribution of wall shear stress in the mother and daughter vessels. Also, the effect of distribution of wall shear stress on the minimization of energy loss and flow resistance is considered. It is shown that constant wall shear stress in the mother and daughter vessels provides the minimum flow resistance and energy loss of biological flows. Moreover, the effects of different wall shear stresses in the mother and daughter branches, different lengths of daughter branches in the asymmetric bifurcations and non-Newtonian effect of biological fluid flows on the bifurcation angle and the relationship between the diameters of mother and daughter branches are considered. Using numerical simulations for non-Newtonian models such as power law and Carreau models, the effects of optimal bifurcation angle on the pressure drop and flow resistance of blood flow in the symmetric bifurcation are investigated. Numerical simulations show that optimal bifurcation angle decreases the pressure drop and flow resistance especially for bifurcations at large Reynolds number.© 2013. Source

Zare M.,Isfahan University of Technology | Daneshi M.,Isfahan University of Technology | Shirani E.,Foolad Institute of Technology | Salimpour M.R.,Isfahan University of Technology
International Journal of Heat and Mass Transfer

Effects of blood vessels in a living tissue subjected to heat transfer radiation are investigated. The heat transfer between blood flowing inside vessels and the tissue around the vessels is considered. For this purpose, temperature distributions in three-dimensional space are evaluated by solving the continuity, momentum and energy equations, numerically. Blood is considered as non-Newtonian fluid using the power law model. A precise and realistic model for skin and blood vessels is used to analyze the transient heat transfer through skin. Skin is considered as a three-dimensional structure including three layers embedded with counter-current vessels, with optimally branched circular cross sectional areas. Results for temperature distribution show that arteries act as heat sinks while veins carry heat out of the upper part of the tissue. It is observed that the role of blood for cooling the tissue under radiation is more significant than what was assumed in previous studies. Also, skin burn degree induced by radiation is evaluated. It was seen that skin burn is a function of time and temperature. Arteries restrict the skin burn-depth while the veins act oppositely. © 2014 Elsevier Ltd. All rights reserved. Source

Shumal M.,Isfahan University of Technology | Nili-Ahmadabadi M.,Isfahan University of Technology | Shirani E.,Foolad Institute of Technology
Aerospace Science and Technology

In the present study, the ball-spine inverse design algorithm is developed for swirling viscous flow regime to improve the performance of an axisymmetric 90-degree bend duct between the radial and axial diffuser of a centrifugal compressor. Performance improvement of the 90-degree bend duct is accomplished to increase its pressure recovery without separation. First, the effects of geometric parameters on flow separation are numerically studied and a safe margin is obtained for prevention of flow separation and stall. Then, the safe margin is enlarged to reach a higher pressure recovery via the shape modification of duct walls. The shape modification process integrates the BSA as shape modification algorithm and an axisymmetric flow analysis code as flow solver. Shape modification process is carried out by improving the current wall pressure distribution and applying it to the inverse design algorithm. Results show merits and robustness of the BSA for duct design in swirling viscous flow regime whereby the pressure recovery coefficient of the 90-degree bend duct increases up to 7%. © 2016 Elsevier Masson SAS. All rights reserved. Source

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