Fluid Mechanics
for the Real World

A course to understand fluid flows and learn to solve problems, one step at a time.

1 Basic flow quantities

Fundamental concepts required to dive into fluid mechanics

1.1 How to think of a fluid

Watch on YouTube: "How to think of a fluid"

1.2 Density

Watch on YouTube: "Density"

1.3 Viscosity

Watch on YouTube: "Viscosity"

1.4 Mass flow and volume flow

Watch on YouTube: "Mass flow and volume flow"

1.5 Fluids respond to things

Watch on YouTube: "Fluids respond to things"

1.6 A first look at turbulence

Watch on YouTube: "A first look at turbulence"

1.7 Critical questions: time dependency

Watch on YouTube: "Critical questions: time dependency"

1.8 Critical questions: Reynolds number

Watch on YouTube: "Critical questions: Reynolds number"

1.9 Turbulence and stability

Watch on YouTube: "Turbulence and stability"

Documents for Chapter 1

theory PDF Chapter 1 - Basic flow quantities Open PDF

Problems PDF Chapter 1 - Basic flow quantities Open PDF

2 Analysis of existing flows

Quantify the forces, moments, and powers associated with an existing flow

2.1 Mass balance

2.2 Visualizing mass balance

2.3 Mass balance: an example

2.4 Mass balance: another example

2.5 Momentum balance

2.6 Visualizing momentum balance

2.7 Momentum balance: an example

2.8 Momentum balance: another example

2.9 Energy balance

2.10 Energy balance: shortcomings

2.11 Energy balance: an example

2.12 Energy balance: “losses”

2.13 Kill the Bernoulli equation

2.14 Non-uniform flows

2.15 Non-uniform flows: basic example

2.16 Unsteady effects

2.17 Non-uniform flows: an example 1/2

2.18 Non-uniform flows: an example 2/2

2.19 Strengths and weaknesses of this method

2.20 Control volumes: towards predicting flows

Documents for Chapter 2

theory PDF Analysis of existing flows will be released week 44

problems PDF Analysis of existing flows will be released week 44

3 Working with pressure and shear

Quantify the effect of pressure and shear in fluids

3.1 Pressure on hard surfaces

3.2 Pressure on hard surfaces: example

3.3 Pressure within fluids

3.4 Special case: buoyancy

3.5 Shear on hard surfaces

3.6 Shear on hard surfaces: example

3.7 Shear within fluids

3.8 Shear perpendicular to a surface

3.9 Shear and velocity

Videos for chapter 3 are planned for completion in Q1 2027

Documents for Chapter 3

theory PDF Working with pressure and shear will be released week 47

problems PDF Working with pressure and shear will be released week 47

4 Prediction of fluid flows:
theory and practice

Understand how fluid flow is calculated using computers (Computational Fluid Dynamics)

4.1 Fields, not trajectories

4.2 Time changes on a grid: example

4.3 Time changes on a grid

4.4 Mass balance equation: general case

4.5 Mass balance equation: incompressible flow

4.6 Momentum balance: general case

4.7 Momentum balance: incompressible flow

4.8 Energy balance

4.9 CFD: discretizing the momentum equation

4.10 CFD: the most basic loop

4.11 CFD: modeling turbulence

4.12 CFD: recap

Videos for chapter 4 are planned for completion in Q1 2027

Documents for Chapter 4

theory PDF Prediction of fluid flows will be released week 49

problems PDF Prediction of fluid flows will be released week 49

5 Deciding what matters

Identify which parameters influence your flow, and which don’t

5.1 Scales in fluid mechanics

5.2 Non-dimensional momentum balance

5.3 Important flow parameters

5.4 Difficulties equating parameters

5.5 Revisiting turbulence

5.5 Comparing results: coefficients

5.6 Comparing results: one example

5.7 Comparing results: another example

5.8 Deciding what matters: recap

Videos for chapter 5 are planned for completion in Q2 2027

Documents for Chapter 5

theory PDF Deciding what matters will be released week 51

problems PDF Deciding what matters will be released week 51

About this course

Olivier Cleynen, PhD, is an engineer, scientist and teacher who likes turning complicated topics into things students can work with.

This course is designed so you can learn how to think like a fluid dynamicist — how to frame problems, compute the key quantities, and decide what is important in your fluid flow.

Olivier wants you to learn:

Which equations will tell you what
How to deal with turbulence
How CFD software works
How to find out what controls a specific flow.

This course is resolutely modern. There are no edge cases or long proofs. To be comfortable here, you will need solid high-school-level math & physics (vectors, calculus, solid mechanics). From there, we progress rapidly but calmly, at a Bachelor/Masters level, in chunks of 11 minutes each.

Contact

Olivier welcomes feedback, trial requests, and inquiries.
To be notified when new videos are released, you can also register for updates.

An undertaking of Beyond Bernoulli Ventures / Olivier Cleynen, Warschauer Straße 13, 39104 Magdeburg, Germany.

Videos are all rights reserved, see terms of use. Background kitesurf image derived from an original photo by Heiner. Portrait photo by Katrin Freund, used under license, all rights reserved. Mailing list operated via Mailchimp. Spam filtering carried out through Akismet. Video streaming through YouTube and Vimeo. While you are here, can I interest you in a good, free-to-download thermodynamics textbook?

Fluid Mechanics for the Real World