Journal ArticleDOI
Separation and reattachment of non-newtonian fluid flows in a sudden expansion pipe
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TLDR
The reattachment lengths for the purely viscous non-Newtonian fluids are found to be almost the same as those for water, while in the turbulent flow regime, theReattachment length for the viscoelastic fluids is two or three times longer than those forWater, and gradually increases with increasing concentration of vis coelastic solutions.Abstract:
In the current flow visualization studies, the role of non-Newtonian characteristics (such as shear-rate-dependent viscosity and viscoelasticity) on flow behavior across the sudden expansion step in a circular pipe is investigated over a wide range of Reynolds numbers including the turbulent flow. The expansion ratios tested are 2.000 and 2.667 and the range of the Reynolds number covered in the current flow visualization tests are 10–35 000 based on the inlet diameter. The reattachment lengths for the viscoelastic fluids in the laminar flow regime are found to be much shorter than those for the Newtonian fluid. In addition they decrease significantly with increasingly concentration of viscoelastic fluid at the same Reynolds number. However, in the turbulent flow regime, the reattachment length for the viscoelastic fluids is two or three times longer than those for water, and gradually increases with increasing concentration of viscoelastic solutions, resulting in 25 and 28 step-height distances for 500 ppm and 1000 ppm polyacrylamide solutions respectively. This may be because the elasticity in polyacrylamide solutions suppresses the eddy motion and controls separation and reattachment behavior in the sudden expansion pipe flow. The reattachment lengths for the purely viscous non-Newtonian fluids are found to be almost the same as those for water.read more
Citations
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An unsteady analysis of non-Newtonian blood flow through tapered arteries with a stenosis
TL;DR: In this article, the problem of non-Newtonian and nonlinear blood flow through a stenosed artery is solved numerically where the nonlinear rheology of the flowing blood is characterised by the generalised Power-law model.
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Investigation of Heat Transfer Enhancement in a Forward-Facing Contracting Channel Using FMWCNT Nanofluids
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Numerical simulation of laminar to turbulent nanofluid flow and heat transfer over a backward-facing step
Hussein Togun,Hussein Togun,Mohammad Reza Safaei,Rad Sadri,Salim Newaz Kazi,Ahmad Badarudin,Kamel Hooman,Emad Sadeghinezhad +7 more
TL;DR: The highest heat transfer augmentation in the present investigation was about 26% and 36% for turbulent and laminar range, respectively compared with pure water.
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Multilaboratory Particle Image Velocimetry Analysis of the FDA Benchmark Nozzle Model to Support Validation of Computational Fluid Dynamics Simulations
Prasanna Hariharan,Matthew Giarra,Varun Reddy,Steven W. Day,Keefe B. Manning,Steven Deutsch,Sandy F. C. Stewart,Matthew R. Myers,Michael R. Berman,Greg W. Burgreen,Eric G. Paterson,Richard A. Malinauskas +11 more
TL;DR: In this paper, the authors evaluate the use and limitations of computational fluid dynamics (CFD) in assessing blood flow parameters related to medical device safety, including mean velocity and turbulent flow quantities.
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A survey on experimental and numerical studies of convection heat transfer of nanofluids inside closed conduits
Mohammad Reza Safaei,Mostafa Safdari Shadloo,Mohammad Shahab Goodarzi,Abdellah Hadjadj,Hamid Reza Goshayeshi,Masoud Afrand,Salim Newaz Kazi +6 more
TL;DR: Nanofluids are solid/liquid suspensions of higher thermal conductivity and viscosity compared to common working fluids as mentioned in this paper, and their application in heat transfer enhancement is prospective. But their performance is limited.
References
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Journal ArticleDOI
Finite Element Analysis of Incompressible Viscous Flows by the Penalty Function Formulation
TL;DR: In this article, a review of recent work and new developments for the penalty function/finite element formulation of incompressible viscous flows is presented, in the context of the steady and unsteady Navier-Stokes equations.
Journal ArticleDOI
Computational and experimental study of a captive annular eddy
Enzo O. Macagno,Tin-Kan Hung +1 more
TL;DR: In this article, the main flow and the captive eddy between it and the walls are analyzed, and it is concluded that the main role of the eddy is to shape the flow with a rather small energy exchange.
Journal ArticleDOI
On the calculation of turbulent heat transport downstream from an abrupt pipe expansion
C. C. Chieng,Brian Launder +1 more
TL;DR: In this paper, the authors reported a numerical study of flow and heat transfer in the separated flow region created by an abrupt pipe expansion and employed an adaptation of the TEACH-2E computer program with the standard model of turbulence.
Journal ArticleDOI
Shear-Layer Flow Regimes and Wave Instabilities and Reattachment Lengths Downstream of an Abrupt Circular Channel Expansion
L. H. Back,E. J. Roschke +1 more
Journal ArticleDOI
Flow characteristics associated with abrupt changes in geometry in the case of highly elastic liquids
R.E. Evans,Kenneth Walters +1 more
TL;DR: In this article, the influence of small changes in corner geometry on flow characteristics in the case of elastic liquids flowing in various contraction geometries was considered and it was shown that it is very difficult to make generalizations from one geometry to another or from one type of non-Newtonian fluid to another.
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