The influence of reynolds number on the entry length and pressure drop for laminar pipe flow

1993 ◽  
Vol 71 (3) ◽  
pp. 472-476 ◽  
Author(s):  
N. Dombrowski ◽  
E. A. Foumeny ◽  
S. Ookawara ◽  
A. Riza
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Pipe Flow ◽  
Entry Length ◽  
Laminar Pipe Flow

Unified Entry Length Correlation for Newtonian, Power Law and Bingham Fluids in Laminar Pipe Flow at Low Reynolds Number.

2000 ◽  
Vol 33 (4) ◽  
pp. 675-678 ◽  
Author(s):  
Shinichi Ookawara ◽  
Kohei Ogawa ◽  
Norman Dombrowski ◽  
Esmail Amooie-Foumeny ◽  
Ahmed Riza
Keyword(s):  
Reynolds Number ◽  
Power Law ◽  
Pipe Flow ◽  
Low Reynolds Number ◽  
Bingham Fluids ◽  
Entry Length ◽  
Low Reynolds ◽  
Laminar Pipe Flow

scholarly journals Laminar Pipe Flow with Mixed Convection under the Influence of Magnetic Field

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 824
Author(s):  
Johannes Rudl ◽  
Christian Hanzelmann ◽  
Steffen Feja ◽  
Anja Meyer ◽  
Annegret Potthoff ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Mixed Convection ◽  
Pipe Flow ◽  
Permanent Magnets ◽  
Local Effect ◽  
Solid Content ◽  
Magnetic Forces ◽  
Order Of Magnitude ◽  
Laminar Pipe Flow

Magnetic influence on ferronanofluid flow is gaining increasing interest from not only the scientific community but also industry. The aim of this study is the examination of the potentials of magnetic forces to control heat transfer. Experiments are conducted to investigate the interaction between four different configurations of permanent magnets and laminar pipe flow with mixed convection. For that purpose a pipe flow test rig is operated with a water-magnetite ferronanofluid. The Reynolds number is varied over one order of magnitude (120–1200). To characterise this suspension, density, solid content, viscosity, thermal conductivity, and specific heat capacity are measured. It is found that, depending on the positioning of the magnet(s) and the Reynolds number, heat transfer is either increased or decreased. The experiments indicate that this is a local effect. After relaxation lengths ranging between 2 and 3.5 lengths of a magnet, all changes disappeared. The conclusion from these findings is that magnetic forces are rather a tool to control heat transfer locally than to enhance the overall heat transfer of heat exchangers or the like. Magnetically caused disturbances decay due to viscous dissipation and the flow approaches the basic state again.

Development Length Requirements for Fully Developed Laminar Pipe Flow of Yield Stress Fluids

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
R. J. Poole ◽  
R. P. Chhabra
Keyword(s):  
Reynolds Number ◽  
Yield Stress ◽  
Pipe Flow ◽  
High Reynolds Number ◽  
Development Length ◽  
Bingham Number ◽  
Nonmonotonic Function ◽  
Yield Stress Fluids ◽  
High Reynolds ◽  
Laminar Pipe Flow

In this technical brief, we report the results of a systematic numerical investigation of developing laminar pipe flow of yield stress fluids, obeying models of the Bingham-type. We are able to show that using a suitable choice of the Reynolds number allows, for high Reynolds number values at least, the development length to collapse to the Newtonian correlation. On the other hand, the development length remains a weak, nonmonotonic, function of the Bingham number at small values of the Reynolds number (Re≤40).

scholarly journals Parametric optimization of a stamped longitudinal vortex generator inside a circular tube of a solar water heater at low Reynolds numbers

2021 ◽  
Vol 3 (8) ◽  
Author(s):  
Felipe A. S. Silva ◽  
Luis Júnior ◽  
José Silva ◽  
Sandilya Kambampati ◽  
Leandro Salviano
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Reynolds Numbers ◽  
Geometric Parameters ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water

AbstractSolar Water Heater (SWH) has low efficiency and the performance of this type of device needs to be improved to provide useful and ecological sources of energy. The passive techniques of augmentation heat transfer are an effective strategy to increase the convective heat transfer coefficient without external equipment. In this way, recent investigations have been done to study the potential applications of different inserts including wire coils, vortex generators, and twisted tapes for several solar thermal applications. However, few researchers have investigated inserts in SWH which is useful in many sectors where the working fluid operates at moderate temperatures. The longitudinal vortex generators (LVG) have been applied to promote heat transfer enhancement with a low/moderate pressure drop penalty. Therefore, the present work investigated optimal geometric parameters of LVG to enhance the heat transfer for a SWH at low Reynolds number and laminar flow, using a 3D periodical numerical simulation based on the Finite Volume Method coupled to the Genetic Algorithm optimization method (NSGA-II). The LVG was stamped over a flat plate inserted inside a smooth tube operating under a typical residential application corresponding to Reynolds numbers of 300, 600, and 900. The geometric parameters of LGV were submitted to the optimization procedure which can find traditional LVG such as rectangular-winglet and delta-winglet or a mix of them. The results showed that the application of LGVs to enhance heat transfer is an effective passive technique. The different optimal shapes of the LVG for all Reynolds numbers evaluated improved more than 50% of heat transfer. The highest augmentation heat transfer of 62% is found for the Reynolds number 900. However, the best thermo-hydraulic efficiency value is found for the Reynolds number of 600 in which the heat transfer intensification represents 55% of the pressure drop penalty.

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