Pressure Drop For Laminar Flow Research Articles

Pressure Drop for Laminar Flow in 3D Straight and Elbow Pipes Using Computational Fluid Dynamics

Designing piping systems for laminar flow requires an understanding of pressure drop. Pressure drop can offer insights for selecting pipe materials, designing an efficient piping system, and choosing the appropriate elbows and fittings. Utilizing numerical simulations, the pressure drop in straight pipes, 45o bends, 90o bends, and 180o bends is examined. Velocity profiles for straight pipes and bends are compared, revealing the increase in pressure drop caused by the bend in comparison to the straight pipe. The numerical simulation results indicate that the bend results in an increased pressure drop in the pipe's flow.

Variation of Pressure Drop along the Straight and Bifurcated Channel: Experiment and Simulation

This paper derives an experimental and simulated investigation carried to analyze the performance of channel for calculating the pressure drop in laminar flow through rectangular shaped (straight and branched) microchannels. The microchannels taken ranged in variable aspect ratio from 0.75 to 1. Every check piece was made from copper and contained only one channel along a direction. The experiments were conducted with normal water, with Reynolds range starting from some 720 to 3500. Predictions obtained supported that with the variation in the aspect ratio the properties of the fluid also change. It is observed that the pressure drop changes with the change in the aspect ratio and flow rate and found that there is a correlation between the experimental and computational model results.

20303 マイクロチャンネル内の二相流圧力損失および流動沸騰熱伝達に関する研究

The pressure drop and the heat transfer characteristics in mini pipes were investigated experimentally. Diameter of the present mini pipes was 0.089mm, respectively. Length of the test pipes channels was 20mm. The test liquid temperature was room-temperature, i.e. 20℃. A range of Reynolds number was 85<Re<384. The Present experimental results for D=0.089mm showed to be in good agreement with the conventional correlations of the pressure drop for laminar flow. The present experimental data for D=0.089mm showed to be similar to value by the conventional correlations for laminar flow.

Thermally dependent viscosity and non-Newtonian flow in a double-pipe helical heat exchanger

A double-pipe helical heat exchanger was numerically studied to determine the effects of thermally dependent viscosity and non-Newtonian flows on heat transfer and pressure drop for laminar flow. Thermally dependent viscosities were found to have very little effect on the Nusselt number correlations for Newtonian fluids; however significant effects on the pressure drop in the heat exchanger were predicted. Changing the flow rate in the annulus can significantly affect the pressure drop in the inner tube, since the average viscosity of the fluid in the inner tube would change due to the change in the average temperature. The effects of non-Newtonian power law fluids on the heat transfer and the pressure drop were determined for laminar flow in the inner tube and in the annulus. The Nusselt number was correlated with the Péclet number for heat transfer in the inner tube. For the annulus, the Nusselt number was found to correlate best with the Péclet number and the curvature ratio. Pressure drop data were compared by using ratios of the pressure drop of the non-Newtonian fluid to a Newtonian fluid at identical mass flow rates and consistency indices.

Numerical simulation of roughness effect on microchannel heat transfer and pressure drop in laminar flow

Roughness effects on the heat transfer and pressure losses in microscale tubes and channels are investigated through a finite element CFD code. Surface roughness is explicitly modelled through a set of randomly generated peaks along the ideal smooth surface. Different peak shapes and distributions are considered; geometrical parameters are representative of tubes in the diameter range from 50 to 150 µm. The use of a sufficiently fine mesh allows the direct computation of tube performances under the assumption of incompressible, fully developed flow; a comparison with the predictions of simplified models is also presented. As a result, in the present computations a significant increase in Poiseuille number is detected for all the configurations considered, while the effect of roughness on the heat transfer rate is smaller and highly dependent on the tube shape.

Experimental study of mixed convection and pressure drop in helically dimpled tubes for laminar and transition flow

This paper presents the experimental results carried out in dimpled tubes for laminar and transition flows and completes a previous work of the authors focused on the turbulent region. It was observed that laminar flow heat transfer through horizontal dimpled tubes is produced in mixed convection, where Nusselt number depends on both the natural convection and the entry region. Employing water and ethylene glycol as test fluids, the following flow range was covered: x ∗=10 −4–10 −2 and Ra=10 6–10 8. The experimental results of isothermal pressure drop for laminar flow showed dimpled tube friction factors between 10% and 30% higher than the smooth tube ones. Moreover, it was perceived that roughness accelerates transition to critical Reynolds numbers down to 1400. Correlations for the laminar friction factor f= f( Re, h/ d) and for the critical Reynolds Re crit= Re crit( h/ d) are proposed. The hydraulic behaviour of dimpled tubes was found to depend mainly on dimple height. In mixed convection, high temperature differences in the cross section were measured and therefore heat transfer was evaluated by a circumferentially averaged Nusselt number. Experimenal correlations for the local and the fully developed Nusselt numbers Nu x= Nu x(x ∗,Ra) and Nu ∞= Nu ∞(Ra) are given. Results showed that at low Rayleigh numbers, heat transfer is similar to the smooth tube one whereas at high Rayleigh, enhancement produced by dimpled tubes can be up to 30%.

Oil, Water And Sand Flow Experiments In a Model H(Jlrizont~d Well

Abstract An experimental investigation has been conducted using a 52 mm laboratory test loop incorporating a section of pipe with longitudinal well slots. Single phase flows with radial and axial flow confirmed the validity of a one dimensional model in predicting pressure gradients for both laminar and turbulent flow. No additional turbulence resulting from the influx could be detected. Experiments using an oilfield sand of median diameter 0.22 mm and either produced water or an oil of viscosity 66 mPa.s showed that there was a threshold velocity for sand transport to occur. Stationary deposits of sand were present at velocities well above the threshold velocity. For sand transport in turbulent flow, the Meyer-Peter equation predicted transport rates as functions of water velocity fairly well at low velocities. The laminar flow pressure drop and sand transport results were quite different from the turbulent flow results. They were also different far the two oils; in neither case was a homogeneous flow model found to be appropriate. For flow with stationary sand deposit, radial influx appeared to reduce axial pressure gradients when the sand in the deposit was fluidized by the influx. Injection of water into the heavy oil containing sand showed that some of the sand was washed out of the oil by the water. The water appeared to migrate to form bubbles near the axis of the pipe, leaving the wall oil-wet. High water cuts and low pressure gradients resulted from water injection. Introduction Although horizontal well were first used more than 50 years ago, they were impractical before the recent developments in drilling and completion had taken place. The number of horizontal well in Saskatchewan has increased markedly, so that it appears they will become the standard production technique by the end of the century. In an attempt to contribute to the application of the method to the heavy oil reservoirs of Western Canada. a five-year multidisciplinary study of the reservoir engineering aspects of horizontal wells has been undertaken by the Saskatchewan Research Council. The project was initiated in 1990 with support from several producing companies and agencies of the governments of Canada. Alberta and Saskatchewan. The research reported herein Consists of a first attempt to examine the flow in a horizontal well in conditions likely to be of interest in reservoir modelling. In order for fluid to flow in a horizontal well there must be a pressure decrease in the downstream direction. If the velocity in the wellhore is very low this pressure gradient may be negligible compared to the pressure difference between tile reservoir and the well. However with thin reservoir and underlying water this may not be the case. The effect of the axial pressure gradient On production was predicted theoretically by Dikken (1990) using a homogeneous fluid model and assuming smooth pipe flow in the wellbore. The complication of multiphase wellbore now were recognized by Stone el al. (1989) who adapted the well-known steam water model RELAP5/MODI (Ranson et al 1982) to the case of flow in a horizontal well.

Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Fluid Through Channels with Insert

An equation of Rabinowitsch-Mooney type has been suggested for approximate calculation of pressure drop in flow of generalized Newtonian fluid through channels with insert both in the region of creeping flow and at higher values of the Reynolds number, and this calculation method has been verified for four types of insert using own numerical solution and experimental results as well as literature data.

Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Liquid Through Channel of Noncircular Cross Section

The paper presents a modification of the equations of Rabinowitsch-Mooney type for an approximate calculation of pressure drop in laminar flow of generalized Newtonian liquid through a straight channel whose cross section forms a simple continuous area. The suitability of the suggested procedure of calculation of pressure drop is demonstrated by the comparison of calculation results with both the published and original results of numerical solution and experiments.

Pressure drop for laminar flow of viscoeleastic fluids in static mixers

Pressure drop for laminar flow of viscoeleastic fluids in static mixers

The prediction of transport parameters in filamentous fermentation broths based on results obtained in pseudoplastic polymer solutions

AbstractTransport phenomena studies on single phase “model” fluids are of limited value in biochemical engineering if they cannot be translated to the heterogeneous systems encountered in real fermentation processes. In this paper we discuss the utility of polymer solutions as models of filamentous fermentation broths for evaluation of: pipeline friction factors and impeller power numbers (turbine and helical ribbon). To a first approximation, polymer solutions can serve as suitable models for the prediction of laminar flow pressure drop in pipelines and turbulent power consumption in stirred tanks. However, results obtained on polymer solutions do not directly apply to filamentous fermentation broths for predictions of laminar flow impeller power consumption and the transition point for turbulent flow in stirred tanks. These discrepancies are believed to result from the existence of a time dependent yield stress in filamentous fermentation broths.

Pressure drop for laminar flow of non-Newtonian fluids in static mixers

Use of static mixers to process viscous non-Newtonian fluids is quite common. Wilkinson and Cliff (1977) have presented pressure drop data for aqueous glycerine solutions (Newtonian fluids) and aqueous 1% polyacrylamide solution showing viscoelastic behavior. They found no difference in friction factor for Newtonian and viscoelastic fluids. Many of the studies are restricted to Newtonian fluids and cover only one size of the static mixer. Therefore, this study is aimed at studying the pressure drop for flow of non-Newtonian inelastic and viscoelastic fluids for static mixer elements of different designs and different sizes.

General Equations for Pressure Drop for Laminar Flow in Ducts of Arbitrary Cross Sections

This paper presents general equations for pressure drop calculations for developed and developing laminar flow in ducts of arbitrary cross sections. The results obtained from these equations compare well with the theoretically calculated values available in the literature for circular, rectangular, triangular, elliptical, polygonal, casped, corner and side ducts. The maximum deviations by these comparisons are 7.3 and −4.0 percent, respectively. Besides these, the equations yield satisfactory results for eccentric and concentric annular ducts.

Pressure drop for laminar flow of non-Newtonian power law fluids in the inlet region of rectangular duct.

In the inlet region and the fully developed region of rectangular duct, the axial pressure drop due to a steady laminar flow of non-Newtonian power law fluid was measured by the multi-tube manometer and the theoretical analysis in our previous paper was discussed on the basis of present experimental result. From this finding, it can be considered that our theoretical analysis is useful to predict the pressure drop in the inlet region of rectangular duct.

Laminar-Flow Pressure Drop in Symmetrical Finite Rod Bundles

Laminar-flow pressure drop in the form of f-Re is presented for rod bundle geometries consisting of a central rod surrounded by four to ten peripheral rods within a containing channel. The influence of varying rod size and peripheral rod circle diameter on the pressure drop has also been reported.

Flow in the Hydrodynamic Entrance Region of Ducts of Arbitrary Cross Section

A general method of analysis is presented for determining the developing velocity field and pressure drop for laminar flow in the entrance region of ducts having arbitrary cross sections. Application of the solution method is made to rectangular ducts and to triangular ducts. Available experimental data are compared with the analytical results and good agreement is found to prevail. Development characteristics for six ducts are brought together and compared, and various trends are identified.

Excess Pressure Drop in Laminar Flow through Sudden Contraction. Non-Newtonian Liquids

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExcess Pressure Drop in Laminar Flow through Sudden Contraction. Non-Newtonian LiquidsGianni Astarita, Guido Greco Jr., and Luigi PelusoCite this: Ind. Eng. Chem. Fundamen. 1968, 7, 4, 595–598Publication Date (Print):November 1, 1968Publication History Published online1 May 2002Published inissue 1 November 1968https://doi.org/10.1021/i160028a011RIGHTS & PERMISSIONSArticle Views155Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (411 KB) Get e-Alerts

Excess Pressure Drop in Laminar Flow through Sudden Contraction. Newtonian Liquids

Excess Pressure Drop in Laminar Flow through Sudden Contraction. Newtonian Liquids

Laminar converging flow of dilute polymer solutions in conical sections: Part I. Viscosity data, new viscosity model, tube flow solution

AbstractThis investigation is reported in two parts. Necessary background information is introduced in Part I. The converging flow investigation proper is described in Part II (18).In Part I, viscosity data are presented for polymer solutions used in the converging flow experiment. These data are fitted with a new three‐parameter viscosity model which fits the data better than previous three‐parameter models. (The viscosity model parameters are used in Part II to characterize rheological behavior of the polymer solutions in the converging flow experiment.) The corresponding relationship between flow rate and pressure drop for laminar flow in cylindrical tubes is derived. (In Part II this relationship is used in deriving an analogous relationship for slow non‐Newtonian flow in conical sections.)The primary purpose of Part I is to provide background information for Part II. However, the new viscosity model and the tube flow relationship are of some interest in themselves. The new viscosity model should prove useful for describing viscosity data of a variety of polymer solutions and polymer melts. A simple procedure for fitting the model to viscosity data is described. The tube flow relationship can be used for predicting pressure losses once the viscosity model parameters have been determined. Conversely, it can be used for determining the viscosity model parameters from tube flow data.

The Effect of Turbulence on Flow of Natural Gas Through Porous Reservoirs

Abstract The nature and the limits of validity of Darcy's law as applied to the flow of natural gas through reservoirs has been considered in order to resolve some controversial aspects of the effect of turbulence on pressure drops. The equivalence between various concepts and viewpoints advanced in the past by several investigators to explain how and why a gas well does not necessarily perform according to Darcy's law is shown. Starting with generalized equations of flow of fluids through porous media, a partial differential equation has been derived which accurately represents the flow at all rates. This equation has been numerically solved using an IBM 704 digital computer. The results permit plots of unsteady radial pressure distribution curves from which specific isochronal backpressure curves may be constructed. These back-pressure curves show the effect of the fl factor on the slope of the back-pressure curve. The calculations further indicate that the drainage radius for a gas well in turbulent flow propagates at a rate dependent upon the rate of production at the wellbore. This is quite different from the case with liquid flow or natural-gas flow in laminar regime. Additionally, the effect of reservoir inhomogeneities and crossflow between layers of different permeability on the back-pressure performance of gas wells has been considered red. In light of the current numerical results the significance and limitation of the rate of flow function Y proposed by Smith has been discussed. Introduction The relationship between the pressure drop and flow rate in problems of fluid flow through porous media is known to be affected by the nature of flow through the porous matrix. It has been observed by many that, for a range of flow rates, the pressure drop remains proportional to the rate of flow. When some flow rate is reached, however, it is usually observed that the pressure drop gradually begins to increase more than proportionally to the flow rate. It is well known that this phenomenon was first observed by Osborne Reynolds in 1901 in experimenting with flow through pipes. In his classical experiments. Reynolds made visual observations on the condition of streamlines evidenced by injecting a dye into water flowing through glass tubes. In these experiments, the abrupt transition between steady, "streamline, laminar" flow and unsteady random turbulent flow was found to be a function of the dimensionless group (D / ), now known as the Reynolds number. During these experiments, in addition to observations on the nature of flow regimes, the proportionality between flow rate and pressure drop in laminar flow was contrasted with the nonlinearity between these variables in turbulent flow. Fancher and Lewis reported data on various consolidated and unconsolidated sands in 1933. Their conclusions were that ". . . the flow of fluids through these porous materials closely resembles that through pipes; that there is a condition of flow in porous systems which resembles viscous flow, another which corresponds to turbulent; that the change from one type to the other takes place at a definite and reproducible condition for each system". In 1947, Brownell and Katz published a method to predict the laminar and turbulent flow behavior from the particle size, bed porosity and the particle sphericity, employing the friction factor-Reynolds number charts for pipes. Several investigators have verified the work of Fancher, Lewis and Barnes and presented their data as friction factor-vs-Reynolds number plots. The equation which would represent the pressure gradient over the whole range of velocity must have an added term over that represented by Darcy's law. Accordingly, the pressure gradient necessary to sustain flow at the velocity (v) through a porous medium may be represented by the following equation, suggested by Forscheimer. = ..........(1) The nature and the range of validity of Darcy's law has been the subject of studies by many investigators over the past years. While everyone seemed to agree on the need for a quadratic correction term to Darcy's law to make it effective over the range of velocities, the concept of inception of turbulence and the use of the term "turbulent flow" remained controversial. JPT P. 799^