## Dr. SaMeH S. Ahmed

Associate Prof. of Environmental Engineering

# Plug flow

fluid mechanicsplug flow is a simple model of the velocity profile of a fluid flowing in a pipe. In plug flow, the velocity of the fluid is assumed to be constant across any cross-section of the pipe perpendicular to the axis of the pipe. The plug flow model assumes there is no boundary layer adjacent to the inner wall of the pipe.

The plug flow model has many practical applications. One example is in the design of chemical reactors. Essentially no back mixing is assumed with "plugs" of fluid passing through the reactor. This results in differential equations that need to be integrated to find the reactor conversion and outlet temperatures. Other simplifications used are perfect radial mixing and a homogeneous bed structure.

An advantage of the plug flow model is that no part of the solution of the problem can be perpetuated "upstream". This allows one to calculate the exact solution to the differential equation knowing only the initial conditions. No further iteration is required. Each "plug" can be solved independently provided the previous plug's state is known.

The flow model in which the velocity profile consists of the fully developed boundary layer is known as pipe flow. In laminar pipe flow, the velocity profile is parabolic.[1]

##  Determination of Plug Flow

For flows in pipes, if flow is turbulent then the laminar sublayer caused by the pipe wall will is so thin that it is negligible. Plug flow will be achieved if the sublayer thickness is much less than the pipe diameter ($delta_s$<<D).

$delta_s = frac {5 u} {u^*}$
$u^* = left (frac { au_w} { ho} ight )^{1/2}$
$au_w = frac {D Delta P} {4 L}$[2]
$frac {Delta P} {L} = frac {f ho V^2} {2D}$[3]
${1 over sqrt{mathit{f}}}= -2.0 log_{10} left(frac{frac{epsilon}{D}}{3.7} + {frac{2.51}{Re sqrt{mathit{f} } } } ight) , ext{(turbulent flow)}$

where f is the Darcy friction factor (from the above equation or the Moody Chart), $delta_s$ is the sublayer thickness, D is the pipe diameter, $ho$ is the density, u* is the friction velocity (not an actual velocity of the fluid), $au_w$ is the shear on the wall, and $Delta P$ is the pressure loss down the length L of the pipe. $epsilon$ is the relative roughness of the pipe. In this regime the pressure drop is a result of inertia-dominated turbulent shear stress rather than viscosity-dominated laminar shear stress.

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### Civil Eng. Students

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### Mining Engineering

Mining engineering is an engineering discipline that involves practice, theory, science, technology, and the application of extracting and processing minerals from a naturally occurring environment. Mining engineering also includes processing minerals for additional value.

### Environmental Engineering

Environmental engineers are the technical professionals who identify and design solutions for    environmental problems. Environmental engineers provide safe drinking water, treat and properly dispose of wastes, maintain air quality, control water pollution, and remediate sites contaminated due to spills or improper disposal of hazardous substances. They monitor the quality of the air, water, and land. And, they develop new and improved means to protect the environment.

### Proverb

Actions speak louder than words

### Univeristies

Universities I've worked in

Assuit University (Home University), Egypt

Imperial College, London, UK

King Saud University, KSA

,Majmaah University

### Also visit

https://www.researchgate.net/profile/Sameh_Ahemd

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### Think

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### Sports

Egypt vs Tunisia (Handball final)  30/1/2016

### Course 2016/17-1

1. Computer Applications in Surveying  CE 473
2. Surveying 1 CE 370
3. Photogrammetry CE 474
4. Surveying II  CE 371
5. Design I  (round 4) CE 498

Rule #7

### Latest

Member of the Editorial Board: " Journal of Water Resources and Ocean Sciences"  2013

Participating in The Third International Conference on Water, Energy and Environment,(ICWEE) 2015 - American University of Sharjah, UAE 24-26 March 2015 with a Paper and Poster

New article

Recovery of Titania from Waste-Sludge of Majmaah Water Treatment Plant

"Production of Titania Nano-particles from Wast-

Sludge

### Coming soon

Results of M2 CE311

### Student Conference

Participation  in the 6Th Student Conference

With a paper and oral presentation

From the Senior Design Project CE499 -35

See inside, the paper, and presentation

## Surveying  I -  CE 370 - 2016-2017-1

 Power point Sheets Lecture notes Second Midterm Exam Results Model Answer

Student Performance Records

## Surveying II - CE 371 - 2016-2017-1

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Student Performance Records

## CE 473

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### 2015-2016-2 - Photogrammetry  CE474

 Available 0-1-2-3-4 Power point Available Quizzes 2 and 3 with model Answer Quizzes Available Chapter 1,2,3,4,5 Lecture notes Report 1  Cameras Report Y 60 marks Exams

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Student Performance Records

## Environmental Engineering 1

CE 360: Environmental Engineering 1

37-2

 Y PP0-1-2-3,4 Power point Y 1,2,3,4,5 Chapters Water quality Poster + Climate Change Reports will be announced (Quiz #2 will be using D2L- Online Quizzes Y Quizzez 2,3 and 4 with model answer and results Exams and results

### Engineering Report Writing

GE 306: Engineering Report Writing

### Senior Design 2 - CE 499

Meeting on 14-4-2015

Second Best paper from Senior Design Projects in 2015

Paper title:

### Evaluation of Groundwater Quality Parameters using Multivariate Statistics- a case Study of Majmaah, KSA

Students:

Abdullah A. Alzeer

Husam K. Almubark

Maijd M. Almotairi

### CE 360-Summer Course

Environmental Engineering I

## Welcome to CE360 second Term 2015-2016

### Engineering Practice

Engineering Practice GE 307

### الهيئة الوطنية للاعتماد والتقويم الاكاديمي

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### Thank you

Your frequent visit to my website has helped  a lot to get the 2nd place in the university competition in the  year 1434-2013... Thanks very mush and please keep following my work

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## CE 212

 Y from PP0 to PP 6 + PDF Power points Y Midterm #2 + Model Answer + results Exams Y lab 3 Labs Solution of Quiz 4 + Results HW

## CE 311

M2+ model Answer + PP 1-9 = PDF 1-9 all are available

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Results of M2

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