INVESTIGATING THE EFFECT OF POLYMER MOLECULAR

WEIGHT ON DRAG REDUCTION PERFORMANCE USING

ROTATING DISK APPARATUS (RDA)

NURUL FATIMAH BINTI ABDUL BASIR

A thesis submitted in fulfillment

of the requirements for the award of the Degree of

Chemical Engineering (Gas Technology)

Faculty of Chemical & Natural Resources Engineering

UNIVERSITI MALAYSIA PAHANG

February 2013

vi

INVESTIGATING THE EFFECT OF POLYMER MOLECULAR WEIGHT ON

DRAG REDUCTION PERFORMANCE USING ROTATING DISK APPARATUS

(RDA)

ABSTRACT

The investigation of turbulent drag reduction, which is caused by the addition of a small

amount of polymer or some other substances to the liquids flowing systems has been the

focus of attention of many scientists for the last decades. Due to the reduction of the

drag, pumping power for the pipeline will significantly reduced and thus will decrease

the cost of electricity in total production cost. In this study, the effect of the presence of

a drag reducing agent (DRA) and its variety of molecular weight on the torque produced

in rotating disk apparatus containing water is investigated. The experimental procedure

was divided into three parts; obtaining several different polymer molecular weights

using ultrasonication method, testing the water using different polymer molecular weight

at different polymer concentration and lastly is adding the different concentration of

surfactant in the fixed concentration of water- polymer solution. Three polymer

molecular weights are obtained by using ultrasonificator method with value of 11.7967

x106

g/mol, 4.830 x106

g/mol and 1.7179 x106 g/mol. A drastic reduction of drag in the

turbulent flow of solutions as evaluated with torque differences in comparison to the

pure solvent can be observed, even when only minute amounts of the additives are

added. The percentage of drag reduction is relatively increases as we increase the

polymer molecular weight and polymer concentration. A maximum drag reduction of

47.62% has been observed at polymer molecular weight of 11. 7697 x106 with polymer

concentration of 200 ppm. In polymer- surfactant complex solution, 29% of drag

reduction were reported with surfactant concentration of 2000ppm.

vii

MENGKAJI KESAN JISIM MOLEKUL POLIMER KE ATAS PENGURANGAN

GESERAN MENGGUNAKAN RADAS CAKERA BERPUTAR

ABSTRAK

Kajian tentang pengurangan geseran dalam pengolakan cecair, yang mana dengan

penambahan sedikit campuran polimer asli atau beberapa bahan cecair yang lain ke

dalam sistem pengaliran cecair telah menjadi tumpuan ramai ahli sains dalam dekad ini.

Dengan pengurangan geseran ini, kuasa pam yang diperlukan untuk mengangkut cecair

telah berjaya dikurangkan dan juga turut mengurangkan kos janakuasa elektrik yang

diperlukan. Dalam kajian ini, kesan kehadiran agen pengurangan geseran dan

kepelbagaian jisim molekul ke atas tork yang dihasilkan di dalam radas cakera berputar

(RDA) yang mengandungi air telah disiasat. Prosedur eksperimen telah dibahagikan

kepada tiga bahagian; mendapatkan beberapa jisim molekul polimer menggunakan

kaedah ultrasonifikator, menguji air menggunakan jisim molekul polimer yang berbeza

pada kepekatan polimer yang berbeza dan yang terakhir menambah kepekatan

„surfactant„ yang berbeza ke dalam larutan air- polimer yang berkepekatan tetap. Tiga

jisim molekul polimer telah diperolehi menerusi kaedah ultrasonifikator dengan nilai

11.7967 x106

g/mol, 4.830 x106

g/mol dan 1.7179 x106 g/mol. Satu pengurangan geseran

yang drastik dalam aliran yang bergelora boleh dilihat apabila terdapat perbezaan tork

dengan pelarut yang tulen walaupun hanya sedikit bahan terlarut ditambah. Peratusan

pengurangan geseran bertambah apabila jisim molekul dan kepekatan polimer

bertambah. Pengurangan geseran yang maksimum iaitu sebanyak 47.62% telah

diperhatikan pada jisim molekul 11.7697 x106 g/mol dengan kepekatan polimer

sebanyak 200 ppm. Dalam larutan kompleks polimer- „surfactant„, pengurangan seretan

sebanyak 29% telah dilaporkan dengan kepekatan „surfactant„ sebanyak 2000ppm.

viii

TABLE OF CONTENTS

PAGE

DECLARATION ii

DEDICATION iv

ACKNOWLEDGEMENT v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS xiv

LIST OF ABBREVIATIONS xv

CHAPTER 1 INTRODUCTION

1.1 Background of Study 1

1.2 Problem Statement 4

1.3 Objectives 5

1.4 Scopes of Study 5

1.5 Rationale and Significance of Study 6

CHAPTER 2 LITERATURE REVIEW

2.1 Types of Fluid flow 9

2.1.1 Laminar Flow 12

2.1.2 Turbulent Flows 13

2.2 Transportation of Crude Oil and Problem Encounter 15

2.2.1 Introduction 15

ix

2.2.2 Transportation by Pipeline 16

2.3 Drag Minimization or Reduction 17

2.3.1 Drag reduction Theories 17

2.3.2 Drag Reduction Agent (DRA) 20

2.3.2.1 Polymer as drag reduction agent 22

2.3.2.2 Surfactant as drag reduction agent 23

2.3.2.3 Fiber as drag reduction agent 26

2.3.2.4 Polymer- Surfactant Complex as reduction

agent 27

2.4 Drag Reduction Mechanism 28

2.5 Rotating Disk Apparatus (RDA) 30

CHAPTER 3 METHODOLOGY

3.1 Equipments 32

3.2 Materials 32

3.3 Rotating Disk Apparatus 33

3.4 Research Methods 35

3.4.1 Polymer Molecular Weight Chain Scission 35

3.4.2 Test Fluid 36

3.5 Experimental Calculation 37

3.5.1 Polymer Analysis 37

3.5.1.1 Polymer Molecular Weight Determination 37

3.5.2 Percentage Drag Reduction Calculation 38

3.5.2.1 Reynold No. Calculation 39

3.6 Experimental Procedures 39

3.7 Summary of Research Procedures 40

3.7.1 Molecular Weight Determination 40

3.7.2 Experimental Procedures on Drag Reduction 41

CHAPTER 4 RESULTS AND DISCUSSION

4.1 Introduction 42

x

4.2 Polymer Molecule Weight Determination 43

4.3 Effect of Polymer Molecular Weight on Drag Reduction 46

4.3.1 Torque Obtained for Different Polymer Molecular

Weight 46

4.3.2 Effect of Different Polymer Molecular

Weight on Drag Reduction 48

4.3.3 Drag Reduction as a Function of Various

Polymer Concentration 52

4.3.4 Effects of Polymer Concentration on Reynold

Number 54

4.3.5 Drag Reduction Efficiency 57

4.4 Polymer- Surfactant Complex Solution Analysis 60

4.4.1 Torque Obtained for Different Surfactant

Concentration 60

4.4.2 Effects of Surfactants Concentration onto

Drag Reduction 64

4.4.3 Effects of Types of Surfactants onto Drag

Reduction 67

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion 70

5.2 Recommendations 75

REFERENCES 77

APPENDICES

Appendix A 82

Appendix B 86

Appendix C 110

xi

LIST OF TABLES

PAGE

Table 3.1 Water Properties at T=293 K and 1 atm 36

Table B.1 Torque Data for Water Only 85

Table B.2 Torque for polymer molecular weight 1 86

Table B.3 Torque for polymer molecular weight 2 89

Table B.4 Torque for polymer molecular weight 3 92

Table B.5 Torque for Polymer MW 1 with Surfactant 1 95

Table B.6 Torque for Polymer MW 1 with Surfactant 2 97

Table B.7 Drag Reduction at polymer molecular weight 11.7696 x106

g/mol

99

Table B.8 Drag Reduction at polymer molecular weight 4.83 x106

g/mol

101

Table B.9 Drag Reduction at polymer molecular weight 1.7179 x106

g/mol

103

Table B.10 Drag reduction for polymer A with various ALS

concentrations

105

Table B.11 Drag reduction for polymer A with various GAELE

concentrations

107

xii

LIST OF FIGURES

PAGE

Figure 2.1 Types of flow inside circular pipelines as goes from laminar,

transition and become turbulent flow 9

Figure 2.2 Laminar Flow in streamline 10

Figure 2.3 Turbulent flow in pipeline 11

Figure 2.4 Schematics on the Surfactants classifications, and their Applications 19

Figure 2.5 Effect of fluid flow before and after injecting DRA 23

Figure 2.6 Schematic diagram of RDA used by Hong et al, (2008) 24

Figure 3.1 Schematic Assembly of Rotary Disk Apparatus 27

Figure 4.1 [ή] of Polymer A as a function of ultrasonic irradiation time at 25⁰C 36

Figure 4.2 Torque as a function of rotational speed for MW 1- 11.77 x106 38

Figure 4.3 Torque as a function of rotational speed for MW 2- 4.83 x106 38

Figure 4.4 Torque as a function of rotational speed for MW 3- 1.7179 x106 39

Figure 4.5 Percentage Drag Reduction as a function of rotational speed for

various Polymer A concentrations at MW of 11.77 x106

40

Figure 4.6 Percentage Drag Reduction as a function of rotational speed for

various Polymer A concentrations at MW of 4.83 x106

41

Figure 4.7 Percentage Drag Reduction as a function of rotational speed for

various Polymer A concentrations at MW of 1.72 x106

41

Figure 4.8 Percentage Drag Reduction versus Polymer A concentration at three

different molecular weights at 2000 rpm 42

Figure 4.9 Percentage Drag Reduction versus Polymer A concentration at three

different molecular weights at 3000 rpm 43

Figure 4.10 Percentage Drag Reduction versus Reynold No for three different

molecular weights at concentration of 18 ppm 44

Figure 4.11 Percentage Drag Reduction versus Reynold No for three different 44

xiii

molecular weights at concentration of 120 ppm

Figure 4.12 Percentage Drag Reduction versus Reynold No for three different

molecular weights at concentration of 200 ppm 45

Figure 4.13 C/ DR versus C for three different molecular weights of Polymer A

at 3000 rpm 47

Figure 4.14 C/DR versus C for unsonicated Polymer A (MW- 1.7697 x106) at

two different rotational speeds 47

Figure 4.15 Resulted torque as a function of RDA rotational speed for various

surfactant concentrations of Ammonium Lauryl Sulfate. 50

Figure 4.16 Resulted torque as a function of RDA rotational speed for various

surfactant concentrations for Glycolic Acid Ethoxylate Lauryl Ether

(GAELE).

50

Figure 4.17 Drag reduction as a function of Reynold No. for various surfactant

concentrations for Ammonium Lauryl Sulfate. 51

Figure 4.18 Drag reduction as a function of Reynold No. for various surfactant

concentrations for Glycolic Acid Ethoxylate Lauryl Ether

(GAELE).

53

Figure 4.19 Drag Reduction as a function of type of surfactant at 2000 rpm and

3000 rpm 54

Figure 4.20 Interactions between polymer and surfactant. 72

Figure C-1 Percentage Drag Reduction as a Function of ALS Concentration at

Three Different Rotational Speeds. 109

Figure C-2 Percentage Drag Reduction as a Function of GAELE Concentration

at Three Different Rotational Speeds. 109

Figure C-3 Torque for Different Concentration of Both Surfactants at 2000 rpm 110

Figure C-4 Torque for Different Concentration of Both Surfactants at 3000 rpm 110

Figure C-5 Percentage Drag Reduction as a Function of Rotational Speed for

Various ALS Concentrations 111

Figure C-6 Percentage Drag Reduction as a Function of Rotational Speed for

Various GAELE Concentrations 111

xiv

LIST OF SYMBOLS

ρ - Density of fluid

μ - Absolute viscosity

v - Kinematic viscosity

ή - Intrinsic Viscosity

xv

LIST OF ABBREVIATIONS

DR(%) - Percentage of drag reduction

DRA - Drag reduction agent

∆P - Pressure drop

∆PL - Pressure loss

Re - Reynolds number

DRmax - Maximum drag reduction

Vavg - Average flow velocity

V - Volumetric flow rate

D - Diameter of pipe

ppmw - Part per million (weight)

K - Polymer- solvent characteristic parameter

[C] - Intrinsic concentration

PSP - Polymer Saturation Point

PDRA - Drag reducing polymer

ALS - Ammonium Lauryl Sulfate

GAELE - Glycolic Acid Ethoxylate Lauryl Ether

1

CHAPTER 1

INTRODUCTION

1.1 Background of Study

Since 60 years ago, drag has been identified as the main reason for the loss of

energy in pipelines and other similar transportation channels due to the turbulence flow

and the friction between flowing fluid and pipe wall surfaces. These energy losses can

be identified through pressure drop, which will results in more pumping power

consumption.

In the turbulent pipeline flow consists of three regions across the pipe diameter

such as the laminar sublayer, the buffer region, and the turbulent core. Fluid near the

pipe wall (the laminar sublayer) tries to stay stationary while fluid in the center region of

the pipe (the turbulent core) is moving quickly. This large difference in fluid velocity

between the laminar sublayer and the turbulent core causes turbulent bursts to occur in

2

the buffer region. Turbulent bursts propagate and form turbulent eddies, which cause

inefficiencies in the hydraulic energy that drives the fluid down the pipeline.

Drag Reducing Agents (DRA) can be classified into three major categories such

as polymers, surfactants and suspended solids. The most effective drag reducing agent

that commonly used in industry is polymers. Toms (1948) first discovered the idea of

drag reduction when he studied the effect of polymer added into a turbulent Newtonian

fluid. He proved that the addition of small amount of polymers which is in ppm in

turbulent flow can produce a significant result in reducing frictional drag. There are two

types of polymer, which are synthetic polymer and natural polymers. Synthetic

polymers are obtained from petroleum oil and mean while natural polymers can be

extracted from resources in nature.

Nowadays, drag reduction is frequently served as a typical approach to save

pumping power in pipelines or other transportation channels and equipments,

particularly those deal with crude oil and refinery products. A pumping power saving

corresponds to the reduction of pressure drop in these medium. Studies on various drag

reduction agent have proven its ability in reducing pressure drop (Li et al., 2006; Cho et

al., 2007; Abdul Bari et al., 2008).

To analyze turbulent drag reduction, most research groups used closed loop pipe

flows, which is using produced pressure difference as drag reduction measurement. In

contrast, this study will use a high-precision rotating disk apparatus (RDA) to measure

3

drag reduction. RDA systems have been used for measuring both the mechanical shear

degradation of polymeric materials and frictional reduction (Choi et al, 1987; Gyr et al,

1995; Choi and Jhon, 1996, Cadot et al, 1998). The flow in the neighborhood of a

rotating disk is a great practical importance, particularly in connection with rotary

machines. In addition, because the rotating disk flow is drag flow with no imposed

pressure gradients, the origin of the turbulent boundary layer is different compared to

the pressure driven flow case in pipelines (Kim et al, 1999). The RDA system,

interfaced with the computer control unit and combines high speed data sampling with

controlled disk rotational speed will accurately measure fluid friction from laminar to

turbulent flow.

According to Kim et al, (1999) flow in rotating disk is used to describe external

flow, the simplest turbulent boundary layer, which occurs on a flat plate at zero

incidences. Many researchers typically studies frictional drag for an internal flow occurs

within pipeline, whereas for an external flow, one studies the total drag (frictional plus

form drag). External flow includes flow over flat plates as well as flow around sub-

merged objects. The drag reduction phenomenon is only related to the frictional part. A

maximum of 80% of the drag reduction can be achieved in tube flow, while the rotating

disk flow generally produces about 50% of the maximum drag reduction because of the

difference in the ratio between the frictional drag and the total drag for tube flow (inner

flow) and rotating disk flow (outer flow).

4

In this investigation, a polymer solution will be mixed in water solution in rotary

disk apparatus. Drag reduction performance will be investigated with varied polymer

molecular weight and concentration correlating with speed of the RDA due to the

injection of polymer. The injection of this polymer can enhance rotating torque and as a

result, the pattern flow will move more smoothly. The benefits when using drag

reducing phenomenon is the allowing of a greater production flow rate at an economical

cost and simultaneously reduction of operating costs such as pumping power.

1.2 Problem Statement

Note that drag reduction is a 60 year old problem associated with originally with

the name Toms as the Toms phenomena, where the addition of even very small (i.e. 5

ppm) of polymeric material can cause the reduction of turbulent drag by 80% in fully

developed boundary layer and channel flows. Drag reduction by polymers in turbulent

flows is an extremely complicated problem. It combines the complexity of turbulent

flow (difficult even for a Newtonian fluid) with the problems of polymer physics; their

combination changes the character of the turbulence and leads to a yet more complex

and difficult problem. Many flows in industrial applications such as oil pipelines are

turbulent flow. The turbulent flow with high velocity in the pipe flow system causes the

formation of eddies or wakes in many different length scales and characterized by larger

pressure drops and larger pumping power requirements than those of laminar flows. The

scale of turbulent eddies in a larger contribution of turbulent energy production to mean

5

mechanical energy loss. The energy losses in the pipe flow system can affect the

production efficiency and economical cost like pumping power. Pump is widely use for

effective fluid transportation before drag reduction phenomenon. The installations of

pump cause the plant more costly because of drag in the turbulent flow. By using pump

into the plant, the higher energy consumption is needed.

1.3 Objectives

Based on the research background and problem statements described in the

previous section, these are the following objectives of this research:

1) To investigate the effect of polymer molecular weights on the drag reduction in

pipeline water system.

2) To study the effect of polymer concentration on percentage of drag reduction in

water system.

3) To study the effect of polymer- surfactant complex solution on percentage of

drag reduction in water system using RDA.

1.4 Scopes of Study

The following scopes have been identified in order to achieve the objectives:

6

1. Three different molecular weight of polymer ( 11.7697 × 106𝑔/𝑚𝑜𝑙, 4.830 ×

106𝑔/𝑚𝑜𝑙 𝑎𝑛𝑑 1.7179 × 106 𝑔/𝑚𝑜𝑙), were produce using ultrasonication method

and were experimented with significance to their effect in the turbulent drag

reduction in rotary disk apparatus.

2. Different polymer molecular weight and concentration will be utilized to

investigate the effect of this polymer used in the drag reduction phenomenon.

3. Distilled water will be the test fluid in this study.

4. The torque readings for pure distilled water and additional of polymer in the

rotary disk apparatus was collected to calculate the corresponding torque,

followed by the percentage of drag reduction.

5. Density and viscosity of pure fluid was used to calculate the Reynolds Number

(NRe) of the fluid.

6. Two different surfactants were used to investigate the effect of polymer-

surfactant complex solution on drag reduction at fixed polymer molecular weight

and concentrations.

1.5 Rationale and Significance of Study

Drag reduction is an alternative way to reduce pumping power losses during

transportation through pipelines. By injecting the drag reduction agent into a pipeline,

the friction pressure losses in a pipeline would be decreased. The significance of this

study was to discover a new scheme to reduce the turbulent drag, which is the main step

7

to the pumping power saving and ultimately lead to cost saving. Furthermore, power

saving is very essential to the cost saving in the plants. Originally from the name Toms

as the Toms phenomena, he said that the addition of even very small (i.e. 5 ppm) of

polymeric material can cause the reduction of turbulent drag by 80% in fully developed

boundary layer and channel flows. It was showed that the presence of turbulence can be

reduced with the addition of small amount of polymer. Also, recently studies found that

the addition of surfactant into a polymer solution could be an effective method in

reducing the mechanical degradation of polymer especially in high temperature flow

system. So, two different surfactants were used to enhance the polymer solution

characteristics.

8

CHAPTER 2

LITERATURE REVIEW

To flow liquid or gas in pipes, energy must be extended to overcome frictional

losses. This energy is extracted from the fluid pressure, which is decrease along the pipe

in the direction of flow. For a fixed pipe diameter, these pressure drops increase with

increasing pipe length until a maximum is reached when the pressure drop along the

pipe is equal to the supply pressure at the beginning of the flow. When flow in the pipe

is turbulent, this maximum flow rate can be increase by the addition of small amounts of

certain high molecular weight polymer to the fluid. These polymers intermingle with the

turbulent flow processes and reduce the frictional pressure. This phenomenon

commonly called drag reduction. Adding small amount of polymer been used in

commercial oil pipelines, fire hoses and storm sewer to increase the flow capacities of

the existing system. It also can be used to reduce supply pressures, pumping cost and

pipe diameter for a given flow capacities.

9

2.1 Types of Fluid Flows

Fluid is a substance that existed in liquid or gaseous phase. The difference

between a solid and fluid is illustrious based on the substance‟s ability to resist an

applied shear or tangential stress that would change its shape. A solid can resist an

applied shear stress and bowed temporarily or permanently depending on the force of

the stress; whereas a fluid will continuously deforms under the influence of the stress

(Cengel and Cimbala, 2006).

Essentially, there are three types of flow in pipeline which are Laminar,

Transitional and Turbulent flow. When calculating heat or mass transfer or head loss, it

is important to know the type of fluid flow whether it is laminar, transitional or turbulent.

Laminar flow happens when dealing with small pipes and low flow velocities. Laminar

flow can be regarded as a series of liquid cylinders in the pipe. Non – laminar flow is

called turbulent flow. Turbulent flow happens at high flow rates and with larger pipes

diameter. In turbulent flow, eddies, wakes or vortexes make the flow is unpredictable

and unstable. The transitional flow actually is a mixture of laminar and turbulent flow.

This happens when the turbulent in the center of pipe and the laminar flow near the

edges. Each of these flows behaves in different equations that predict their behavior and

have different manners in terms of their frictional energy loss while flowing in the

pipelines (Witold, 2008).

10

In these cases, turbulent or laminar flow in circular pipeline could be determined

by the dimensionless Reynolds Number. As discovered by Osborne Reynolds (1842 –

1912) the Reynolds number is important in analyzing at any type of flow when there is

substantial velocity gradient such as shear. The Reynolds number is proportional to

inertial force that divided by viscous force.

𝑅𝑒 =𝐼𝑛𝑒𝑟𝑡𝑖𝑎𝑙 𝑓𝑜𝑟𝑐𝑒𝑠

𝑉𝑖𝑠𝑐𝑜𝑢𝑠 𝑓𝑜𝑟𝑐𝑒𝑠=

𝑉𝑎𝑣𝑔𝐷

𝑣=

𝜌𝑉𝑎𝑣𝑔𝐷

𝜇 (2.1)

Where D is diameter of the pipe in m, ρ is the density of the fluid in kg/m³, V is the

average velocity of the object relative to the fluid (m/s), μ is the dynamic viscosity of

the fluid (Pa·s or N·s/m² or kg/(m·s)). (Geankoplis, 2003)

However, if calculation involved investigation of fluid flow using rotary disk

apparatus (RDA), equipment that used to describe external flow, Reynold number for

rotational flow is described by Kim et al (2001) as

𝑁𝑅𝑒 =𝜌𝜔𝑟2

𝜇 (2.2)

Where r is fluid density, ω is angular velocity [2 p× (revolutions per minute)/60

rad/s], r is radius of disk and μ is fluid viscosity [Pa·s]. Kim et al (2001) also state that

the flow becomes turbulent in an RDA at a critical Reynold number of 3 ×105. Critical

Reynolds number, Recr is the value where the flow becomes turbulent and this value

11

varies for different geometries and flow conditions. The transition from laminar to

turbulent flows is also dependent on other factors; such as pipe surface roughness,

surface temperature, vibration and fluctuations in the flow

At high Reynolds numbers, the inertial forces, which are proportional to the fluid

density and the square of the fluid velocity, are more significant compared to viscous

forces, and therefore the viscous forces cannot inhibit the random and rapid fluctuation

of the fluid. This condition of flow is known as turbulent flow and Reynold number can

be defined as above than 4000 (NRe ˃4000). Whereas in low or moderate Reynolds

number that is less than 2300 (NRe < 2300), the viscous forces are significant enough to

restrict the fluid fluctuation and keep the fluid under smooth ordered motion; and this is

known as laminar flow. In most practical conditions, having Reynolds in-between 2000

until 4000(2000 < NRe < 4000), is called transitional flow (Cengel and Cimbala, 2006).

12

Figure 2.1 Types of flow inside circular pipelines as goes from laminar, transition

and become turbulent flow.

(Source: http://www-

mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/fprops/pipeflow/no

de8.html)

2.1.1 Laminar Flow

At low velocities, where the layers of the fluids seem to slide by one another

without eddies or swirls being present, the flow is called laminar and holds the

Newton‟s law of viscosity (Geankoplis, 2003). Hoener (1965) has defined Laminar flow

as „state of flow where the various fluid sheets do not mix with each other‟. It also is

described as a uniform stable streamline flow without any mixing between layers. Other

than that, laminar flow also defined as steady state flow in which the liquid flows

13

through the pipe smoothly in laminations (E.Shashi Menon et.al, 2005). It can be

consider as a smooth motion of the fluid as the objects goes through it. As the flow rate

increases, more and more disturbance or eddies are formed due to friction between the

adjacent layers of the liquid as well as friction between the pipe wall and the liquid

(E.Shashi Menon et.al, 2005).

A simple summary about laminar flow are low velocity, dye does not mix with

water, fluid particles move in straight lines, simple mathematical analysis possible and

rare in practice in water systems (Andrew ,2008).

Figure 2.2 Laminar Flow in streamline.

(Source: http://www.ceb.cam.ac.uk/pages/hydrodynamic-voltammetry.html)

2.1.2 Turbulent Flows

When a flowing fluid is being obstructed by a bend, valve or even the roughness

of the pipe wall, compression would take place. When this happens, local temperature

and pressure of the fluid will increase. This will results in a turbulent flow as the