Podcast
Questions and Answers
What is the principal focus of the Navier-Stokes equation derivation?
What is the principal focus of the Navier-Stokes equation derivation?
- Reduction steps from the law of thermodynamics
- The impact of gravitational forces on fluid flow
- Reduction steps from Cauchy's equation of motion (correct)
- The study of isothermal and non-isothermal flows
Which equation is essential for estimating flow properties such as velocity and pressure?
Which equation is essential for estimating flow properties such as velocity and pressure?
- Euler's equation
- Cauchy’s equation of motion
- Continuity equation (correct)
- Bernoulli's equation
In which scenario do velocity variations occur according to the content?
In which scenario do velocity variations occur according to the content?
- Flow in a pipe bend (correct)
- Static fluid at rest
- Uniform flow through a straight pipe
- Laminar flow in open channels
What is indicated by the operational form of Cauchy’s equation of motion?
What is indicated by the operational form of Cauchy’s equation of motion?
What does the linear momentum balance relate to in fluid dynamics?
What does the linear momentum balance relate to in fluid dynamics?
Which of the following best describes energy dissipation in fluid flow?
Which of the following best describes energy dissipation in fluid flow?
How can the velocity field in a pipe be characterized?
How can the velocity field in a pipe be characterized?
Which of the following is not part of the foundation for modeling a flow system?
Which of the following is not part of the foundation for modeling a flow system?
What characterizes a Newtonian fluid?
What characterizes a Newtonian fluid?
In the context of incompressible fluids, what remains constant?
In the context of incompressible fluids, what remains constant?
For a non-Newtonian fluid, how are the viscous friction terms modified?
For a non-Newtonian fluid, how are the viscous friction terms modified?
In the given velocity field, what does the variable 𝑏 represent?
In the given velocity field, what does the variable 𝑏 represent?
Which assumption is NOT applicable in the provided scenario of fluid flow?
Which assumption is NOT applicable in the provided scenario of fluid flow?
What is the primary purpose of the Navier-Stokes equation in fluid dynamics?
What is the primary purpose of the Navier-Stokes equation in fluid dynamics?
What does the term 'steady flow' imply in fluid dynamics?
What does the term 'steady flow' imply in fluid dynamics?
In the given velocity field, what does the constant 𝑐 represent?
In the given velocity field, what does the constant 𝑐 represent?
What is the primary goal of modifying Cauchy’s equation of motion into an alternative form?
What is the primary goal of modifying Cauchy’s equation of motion into an alternative form?
In the context of Cauchy's equations, what is the significance of having zero degrees of freedom?
In the context of Cauchy's equations, what is the significance of having zero degrees of freedom?
Which component of the Cauchy’s equation corresponds to the gravitational force acting in the x-direction?
Which component of the Cauchy’s equation corresponds to the gravitational force acting in the x-direction?
What does the symbol 𝜏 represent in the alternative form of Cauchy’s equation?
What does the symbol 𝜏 represent in the alternative form of Cauchy’s equation?
How many unknowns are associated with pressure, P, in the context of Cauchy’s equations?
How many unknowns are associated with pressure, P, in the context of Cauchy’s equations?
Which of the following represents the relationship between known and unknown variables in Cauchy’s equation?
Which of the following represents the relationship between known and unknown variables in Cauchy’s equation?
In the y-direction form of Cauchy’s equation, what does the term 𝜏𝑥𝑦 represent?
In the y-direction form of Cauchy’s equation, what does the term 𝜏𝑥𝑦 represent?
Which of the following is included in the modifications made to Cauchy’s equation for the x-direction?
Which of the following is included in the modifications made to Cauchy’s equation for the x-direction?
What is the general form of the equation representing forces in the x-direction?
What is the general form of the equation representing forces in the x-direction?
Which term represents the effects of fluid momentum in the x-direction?
Which term represents the effects of fluid momentum in the x-direction?
What does the symbol $
abla P$ represent in these equations?
What does the symbol $ abla P$ represent in these equations?
How are the directions of tensors represented in these equations?
How are the directions of tensors represented in these equations?
In the equation for the z-direction, which components are explicitly mentioned?
In the equation for the z-direction, which components are explicitly mentioned?
What does the term $
ho v_x v_y$ signify in the context of the equations?
What does the term $ ho v_x v_y$ signify in the context of the equations?
Cauchy’s equation was introduced primarily to address what?
Cauchy’s equation was introduced primarily to address what?
Which of the following is NOT a term found in the equations for the y-direction?
Which of the following is NOT a term found in the equations for the y-direction?
What is the primary assumption regarding the function of velocity components in the x-direction?
What is the primary assumption regarding the function of velocity components in the x-direction?
Which differential term is specifically omitted in the equation for the y-direction?
Which differential term is specifically omitted in the equation for the y-direction?
What is the relationship of $v_y$ as expressed in the simplified Navier-Stokes equations?
What is the relationship of $v_y$ as expressed in the simplified Navier-Stokes equations?
In the Navier-Stokes equations, what does the term $\mu$ represent?
In the Navier-Stokes equations, what does the term $\mu$ represent?
How does the pressure gradient relate to the x-coordinate based on the Navier-Stokes equation?
How does the pressure gradient relate to the x-coordinate based on the Navier-Stokes equation?
What happens when you integrate the expression for $\partial P / \partial y$?
What happens when you integrate the expression for $\partial P / \partial y$?
In the Navier-Stokes equations, what is the significance of steady-state conditions?
In the Navier-Stokes equations, what is the significance of steady-state conditions?
Which of the following describes how $v_x$ is affected by the x-coordinate based on the equation provided?
Which of the following describes how $v_x$ is affected by the x-coordinate based on the equation provided?
What effect does the term $\rho g_y$ have in the y-direction Navier-Stokes equation?
What effect does the term $\rho g_y$ have in the y-direction Navier-Stokes equation?
Which of the following variables plays a key role in determining the final expression for pressure $P(x,y)$?
Which of the following variables plays a key role in determining the final expression for pressure $P(x,y)$?
What does the term $a^2$ signify in the equations for velocity components?
What does the term $a^2$ signify in the equations for velocity components?
What does the integration of the expression $\partial P / \partial y$ ultimately yield in terms of function?
What does the integration of the expression $\partial P / \partial y$ ultimately yield in terms of function?
What significance does the term $\partial^2 v_y / \partial y^2$ hold in the context of fluid dynamics?
What significance does the term $\partial^2 v_y / \partial y^2$ hold in the context of fluid dynamics?
When integrating the expression for $h_x$, what final form does it take in relation to pressure?
When integrating the expression for $h_x$, what final form does it take in relation to pressure?
What is referred to as the rate of increase in length per unit length in linear strain?
What is referred to as the rate of increase in length per unit length in linear strain?
What is the formula for shear strain rate between two perpendicular lines initially intersecting at a point?
What is the formula for shear strain rate between two perpendicular lines initially intersecting at a point?
Which equation represents the linear strain rate tensor for the x-component?
Which equation represents the linear strain rate tensor for the x-component?
In shear strain rates, what expression defines 𝜀𝑦𝑥?
In shear strain rates, what expression defines 𝜀𝑦𝑥?
What does the stress tensor relate to in the context of velocity?
What does the stress tensor relate to in the context of velocity?
In the Navier-Stokes equation, which term represents viscous stress?
In the Navier-Stokes equation, which term represents viscous stress?
How is the stress tensor for the x-direction expressed in the context of the Navier-Stokes equations?
How is the stress tensor for the x-direction expressed in the context of the Navier-Stokes equations?
Which of the following terms appears in the Cauchy’s equations for fluid motion?
Which of the following terms appears in the Cauchy’s equations for fluid motion?
Which of the following represents the relationship between stress and strain rate in a Newtonian fluid?
Which of the following represents the relationship between stress and strain rate in a Newtonian fluid?
What is considered an assumption in the reduction to the Navier-Stokes equations?
What is considered an assumption in the reduction to the Navier-Stokes equations?
In the context of pressure, which term in the Navier-Stokes equations denotes pressure gradient force?
In the context of pressure, which term in the Navier-Stokes equations denotes pressure gradient force?
Which set of terms contributes to the nonlinear forces in the Navier-Stokes equations?
Which set of terms contributes to the nonlinear forces in the Navier-Stokes equations?
What does the symbol 𝜇 represent in fluid mechanics?
What does the symbol 𝜇 represent in fluid mechanics?
What does modifying the Navier-Stokes equations aim to achieve?
What does modifying the Navier-Stokes equations aim to achieve?
Flashcards
Cauchy's Equation of Motion
Cauchy's Equation of Motion
Cauchy's equation of motion is a fundamental equation in fluid dynamics that describes the motion of a fluid element. It expresses the balance of forces acting on a fluid element, including inertial forces, pressure forces, and viscous forces.
Navier-Stokes Equation Derivation
Navier-Stokes Equation Derivation
The Navier-Stokes equation is a set of partial differential equations that describe the motion of viscous, incompressible fluids. It is derived from Cauchy's equation of motion by introducing viscous forces.
Navier-Stokes Equation Applications
Navier-Stokes Equation Applications
The Navier-Stokes equation is a powerful tool for understanding and predicting fluid flow behavior in various engineering applications. It is used to model and analyze fluid flow in pipes, around objects, and in many other scenarios.
Continuity Equation
Continuity Equation
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Flow in a Pipe
Flow in a Pipe
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Flow Around Objects
Flow Around Objects
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Flow in a Bend
Flow in a Bend
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Isothermal Flow
Isothermal Flow
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Cauchy's Equation
Cauchy's Equation
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Pressure (P)
Pressure (P)
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Viscous stress (𝝉)
Viscous stress (𝝉)
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Gravitational acceleration (g)
Gravitational acceleration (g)
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Density (ρ)
Density (ρ)
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Fluid velocity (v)
Fluid velocity (v)
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Fluid acceleration (a)
Fluid acceleration (a)
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Velocity gradient (∇v)
Velocity gradient (∇v)
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Alternative form of Cauchy's equation
Alternative form of Cauchy's equation
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Degree of Freedom in Cauchy's Equations
Degree of Freedom in Cauchy's Equations
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Pressure (P) in Cauchy's Equation
Pressure (P) in Cauchy's Equation
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Stress Tensor (𝝉) in Cauchy's Equation
Stress Tensor (𝝉) in Cauchy's Equation
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Gravitational Acceleration (g) in Cauchy's Equation
Gravitational Acceleration (g) in Cauchy's Equation
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Velocity (v) in Cauchy's Equation
Velocity (v) in Cauchy's Equation
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Density (ρ) in Cauchy's Equation
Density (ρ) in Cauchy's Equation
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Newtonian fluid
Newtonian fluid
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Incompressible fluid
Incompressible fluid
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Navier-Stokes Equation
Navier-Stokes Equation
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Non-Newtonian Fluid
Non-Newtonian Fluid
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Steady flow
Steady flow
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Two-dimensional flow
Two-dimensional flow
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Gravity force
Gravity force
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Linear Strain Rate
Linear Strain Rate
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Shear Strain Rate
Shear Strain Rate
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Strain Rate Tensor
Strain Rate Tensor
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Strain Rate Tensor as a function of velocity
Strain Rate Tensor as a function of velocity
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Stress Tensors as a function of velocity
Stress Tensors as a function of velocity
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Relationship between Strain Rate and Stress Tensor
Relationship between Strain Rate and Stress Tensor
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Simplified Navier-Stokes Equation
Simplified Navier-Stokes Equation
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Derivation of Navier-Stokes Equation from Cauchy's Equation
Derivation of Navier-Stokes Equation from Cauchy's Equation
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Navier-Stokes Equation in Different Coordinate Systems
Navier-Stokes Equation in Different Coordinate Systems
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Navier-Stokes Equation for the x-direction
Navier-Stokes Equation for the x-direction
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Navier-Stokes Equation for y and z directions
Navier-Stokes Equation for y and z directions
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Applications of Navier-Stokes Equation
Applications of Navier-Stokes Equation
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Simplifications of the Navier-Stokes Equation
Simplifications of the Navier-Stokes Equation
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What is the Navier-Stokes equation?
What is the Navier-Stokes equation?
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How are Navier-Stokes equations simplified?
How are Navier-Stokes equations simplified?
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What is the significance of velocity component relationships?
What is the significance of velocity component relationships?
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How are simplified Navier-Stokes equations solved?
How are simplified Navier-Stokes equations solved?
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How is pressure gradient related to velocity components?
How is pressure gradient related to velocity components?
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How is the pressure gradient in the y-direction determined?
How is the pressure gradient in the y-direction determined?
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How is the pressure distribution obtained from the pressure gradient equations?
How is the pressure distribution obtained from the pressure gradient equations?
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What is the process of obtaining the pressure distribution from the pressure gradient equations?
What is the process of obtaining the pressure distribution from the pressure gradient equations?
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What factors influence the pressure distribution?
What factors influence the pressure distribution?
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What kind of function is the pressure distribution?
What kind of function is the pressure distribution?
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What are the pressure gradients in the x and y directions?
What are the pressure gradients in the x and y directions?
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How are the integration constants in the pressure distribution equation determined?
How are the integration constants in the pressure distribution equation determined?
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What is the importance of pressure distribution in fluid flow analysis?
What is the importance of pressure distribution in fluid flow analysis?
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What is the significance of the simplified Navier-Stokes equation in studying pressure distribution?
What is the significance of the simplified Navier-Stokes equation in studying pressure distribution?
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Study Notes
Fluid Mechanics 2 - KIL 3002
- Course code: KIL 3002
- Course title: Fluid Mechanics 2
- Department: Chemical Engineering
- University: Universiti Malaya
Chapter 6: Derivation of Navier-Stokes Equations
- Derivation steps: Reduction steps from Cauchy's equation of motion
- Cauchy's equation of motion: An equation of motion which includes stress tensor terms
- Navier-Stokes equation: Results from the reduction of Cauchy's equation of motion
Derivation of Navier-Stokes Equations
- Reduction of equation from Cauchy's equation of motion, with the simplification of viscosity terms as a function of velocity
- Navier-Stokes equation's components can be expressed as a function of velocity components
- Constitutive equation relates viscous stress tensors with strain rates
- Formula: τij = 2µεij
Determination of Flow Properties
- Modeling a flow system estimates flow velocity and pressure at different locations
- Methods are derived from the law of physics
- Conservation of mass (Continuity equation)
- Linear momentum balance (Navier-Stokes equation)
- Flow patterns and energy dissipations are factors to consider for modeling
Cauchy's Equation of Motion
- Original form: complex, uses 2nd-order tensors
- Alternative form: introduced to overcome complexity and limitations of the original form
- Variables: Pressure (P), Velocities (vx, vy, vz), Stress tensors (Txx, Tyx, Tzx, Tyy, Tzy, Tzz)
- Degree of freedom relates to the number of equations and unknowns.
Reduction to Navier-Stokes Equations
- Simplifying the stress tensor components in terms of velocity components
- Constitutive equation relates viscous stress tensors with strain rates, valid for incompressible and Newtonian fluids.
- Formula: τij = 2µεij
- Strain rate tensor relation to velocity components using different relations.
Reduction to Navier-Stokes Eqn for X-Direction
- Substituting stress tensors in Cauchy's equations yields the Navier-Stokes equation for the x-direction.
- Includes density, pressure, viscosity, and velocity components.
- Relevant for Newtonian fluids.
Reduction to Navier-Stokes Eqn - Simplifications
- Simplifying the Navier-Stokes equations for incompressible fluids, setting ∇•v = 0.
- Resultant equations have reduced complexity, making calculations more manageable for incompressible fluids.
- Compact notation for easier handling of variables.
Navier-Stokes Equation - Compact Form
- Combining the x, y, and z-components of the Navier-Stokes equation to form a general form for any direction.
- Simplified notation to represent the three equations of motion using compact notation.
- General form of the Navier-Stokes equation allows for a general solution for any direction (x,y,z).
Navier-Stokes Equation Applications
- Assumptions made—Newtonian fluid, constant kinematic viscosity (µ), constant density (ρ), and incompressible fluids, flow is steady and 2-dimensional, gravity is negligible.
Application of Navier-Stokes Equation – Example
- Example of a steady, two-dimensional, incompressible velocity field.
- Determining the pressure field as a function of x and y
- Simplification of the Navier-Stokes to solve for x and y components of the equations
- Pressure field functions are determined by using integration techniques and by substituting equations to solve for the differential variables for x and y components.
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