1.1 - Prof. Mohammad Saud Afzal
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Introduction to Viscous Fluid Flow
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Welcome, students! Today we are starting our journey into viscous fluid flow. Can anyone tell me how fluids differ from solids?
Fluids continuously deform under shear force, while solids do not?
Exactly! Fluids cannot resist shear, which is a key characteristic. Now, what are the primary classifications of matter in thermodynamics?
They are classified into solids, liquids, and gases.
Correct! But in fluid mechanics, we primarily categorize matter as fluids — both liquids and gases. Remember, knowing these distinctions is vital for understanding fluid dynamics!
Properties of Fluids
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Let’s delve deeper into fluid properties. What are kinematic properties, and can anyone give examples?
Properties like velocity, acceleration, and vorticity.
Great! Kinematic properties describe how a fluid moves. Now, what about transport properties?
Transport properties include viscosity and thermal conductivity.
Well done! Lastly, can someone outline what thermodynamic properties are?
Density, pressure, temperature, and entropy.
Exactly! Keep these properties in mind as they're fundamental for our next steps into viscous fluid dynamics.
Material Derivatives
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Now, let’s discuss material derivatives. Who can explain what a substantial derivative is?
Is it the time rate of change of a property as it moves through a fluid?
Exactly! Material derivatives track changes based on fluid movement. If we denote a fluid property as Q and the velocity field as V, what would be the formula for the total derivative dQ?
It’s written as dQ/dt = ∂Q/∂t + V · ∇Q.
That's right! This equation is crucial in understanding how properties change as fluid elements move.
Fluid Element Motion and Deformation
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Let’s consider how a fluid element moves. How many types of motion or deformation can a fluid undergo?
Translation, rotation, extensional strain, and shear strain!
Correct! Each of these motions contributes to fluid dynamics. Let’s also discuss how we can visualize these deformations.
Using diagrams to show the positions of fluid elements over time?
Yes! Diagrams help visualize changes in fluid positions, aiding in understanding motion dynamics, which leads us to derive significant equations in fluid mechanics.
Applying Concepts to Derive Navier Stokes
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
As we wrap up, our main objective is to derive Navier Stokes equations. What foundational knowledge do we need before starting this derivation?
Understanding material derivatives and the physical properties of fluids.
Exactly! This preparation will support our derivation process in the upcoming lectures. Keep revisiting these concepts, as they form the bedrock of what’s to come.
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
In this introductory section, students will explore the principles of viscous fluid flow, differentiate between fluids and solids, and learn about fluid properties. The objective is to derive the Navier Stokes equation over several lectures, emphasizing hand-derived mathematics rather than slide-based instruction.
Detailed
Introduction to Viscous Fluid Flow
In this section, Professor Mohammad Saud Afzal begins the lecture series on viscous fluid flow, progressing from basic particle dynamics to the derivation of the Navier Stokes equation. Fluid mechanics distinguishes between fluids (liquids and gases) and solids, where a fluid is defined as a matter that continuously deforms under shear force. The lecture outlines essential properties of fluids, such as:
- Kinematic Properties: Including velocity, acceleration, vorticity, and angular velocity.
- Transport Properties: Such as viscosity and thermal conductivity.
- Thermodynamic Properties: Including density, pressure, and temperature.
The focus on deriving the Navier Stokes equation highlights the importance of material derivatives in fluid behavior, alongside discussions on motion types (translations, rotations, extensional strains, and shear strains). The analysis includes geometric considerations illustrated through fluid element transformations and culminates in deriving significant equations relevant to fluid dynamics.
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Introduction to the Lecture
Chapter 1 of 5
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
Welcome students. So, this is the week 10, lecture number 1, here we are going to study about the topic that is mentioned in this slide, this is about viscous fluid flow. Actually, you have, we have gone through this topic before but in a much more crude manner. The main objective of this module is going to be able to derive Navier Stokes equation from scratch, so how to start from the beginning and derive the Navier Stokes equation.
Detailed Explanation
In this introductory segment, the professor welcomes the students to the first lecture of week 10, focusing on viscous fluid flow. He acknowledges that they have previously encountered this topic but in a less detailed way. The main aim of the module is to derive the Navier-Stokes equation, which is fundamental in fluid mechanics, from the ground up, ensuring that students grasp the entire derivation process.
Examples & Analogies
Think of the derivation of the Navier-Stokes equation like building a house. In a previous course, the students might have seen a house in its initial stages, like just the foundation without walls or a roof. Now, in this module, they will learn how to construct each section of the house step by step, ensuring everything is well-built and understood before they move to the next parts.
Structure of the Module
Chapter 2 of 5
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
And we are expecting to dedicate around depends but at least 3 to 4 lectures in this module and our difference from the regular classes to this one is going to be that I will be teaching it by hand, we will take the help of slides as little as possible, because Navier Stokes equation is something that needs to be done by hand and in the derivation using the slide, it has been found out it is not helpful that much for this particular thing.
Detailed Explanation
The professor anticipates that this module will take about 3 to 4 lectures. He emphasizes that the teaching approach will differ from regular classes, as he plans to perform derivations manually on the board rather than relying on slides. This hands-on approach is deemed necessary for comprehending the complexities involved in the Navier-Stokes equation.
Examples & Analogies
Imagine learning to ride a bicycle. You can watch videos or read about it, but until you actually sit on the bike and balance yourself, practicing is the best way to learn. Similarly, the professor believes that writing down the equations by hand will help students learn more effectively than just looking at slides.
Basics of Fluid Mechanics
Chapter 3 of 5
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
So, to start with this one, some general, you know points; one is a fluid is a substance that deforms continuously under the action of a shear force, this means, it cannot resist shear. A solid however, can resist shear and remain at rest.
Detailed Explanation
The professor explains that a fluid is defined as a material that continuously deforms when subjected to shearing forces, indicating that it cannot maintain its shape when force is applied. In contrast, a solid maintains its shape and resists such forces.
Examples & Analogies
Consider how honey behaves compared to a block of wood. When you pour honey, it flows and changes shape easily because it cannot resist shear forces. On the other hand, the wood block stays intact whether you push it or not. This difference illustrates why fluids and solids have distinct behaviors under stress.
Classification of Matter
Chapter 4 of 5
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
In fluid mechanics, a matter is classified into fluids and non-fluids. So, in thermodynamics, the normal definition is classification in solids, liquids and gases. But in fluid mechanics, it is fluids which consists of gases and liquids and non-fluids; non-fluids are mostly the solids.
Detailed Explanation
The classification of matter in fluid mechanics is based on its ability to flow. Fluids encompass both gases and liquids, while non-fluids are primarily solids. This distinction highlights the different behaviors that materials exhibit when subjected to forces.
Examples & Analogies
Think about pouring water (a fluid) from a glass compared to trying to pour a piece of rock (a solid). The water flows freely and takes the shape of whatever container you put it in, demonstrating fluid behavior, whereas the rock stays the same shape and does not flow.
Properties of Fluids
Chapter 5 of 5
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
So, another basic revision is properties of fluid, so first is kinematic property, that is, velocity, acceleration, vorticity, rate of strain, angular velocity etc.
Detailed Explanation
The professor reviews fluid properties, starting with kinematic properties, which include velocity, acceleration, vorticity, rate of strain, and angular velocity. These properties describe how fluids behave and change when in motion.
Examples & Analogies
Consider how water flows down a river. The velocity tells us how fast it's moving, the acceleration indicates how quickly it speeds up or slows down, and vorticity describes the swirling motions you might see. These terms help us understand the dynamic nature of fluid movement.
Key Concepts
-
Fluid Definition: A substance able to flow and be shaped by external forces.
-
Viscous Flow: Flow characterized by the resistance of fluid layers moving past each other.
-
Navier Stokes Equation: Set of equations governing the dynamics of fluid motion.
Examples & Applications
Example of a viscous fluid: Honey flows slowly compared to water due to its higher viscosity.
In aviation, the Navier Stokes equations are essential in predicting airflow over wings.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
Fluids can flow, and solids stand still; shear makes them change, that's the thrill.
Stories
Imagine honey and water in jars. Honey moves slowly, but water flows with ease. This difference shows viscosity in a breeze.
Memory Tools
Remember 'VVVV' for Kinematic Properties: Velocity, Vorticity, and Variation.
Acronyms
Use 'DROPS' for remembering types of fluid motion
Dilation
Rotation
Order
Pressure
Shear.
Flash Cards
Glossary
- Fluid
A substance that deforms continuously under the action of a shear force.
- Viscous Flow
The flow of fluids that contains internal friction, affecting how they move.
- Navier Stokes Equation
Fundamental equations that describe the motion of viscous fluid substances.
- Kinematic Properties
Properties describing the motion of fluid particles, including velocity and acceleration.
- Material Derivative
The derivative that accounts for changes in a fluid property as it moves with the fluid itself.
Reference links
Supplementary resources to enhance your learning experience.