# ME651 - Fluid Dynamics

#### Instructor

Prof. Avishek Ranjan

#### Section

No separate sections S1/S2 in the course. It is a PG core course, and hence predominantly taken by DD (TFE)’s or M.Techs

#### Semester

Spring’19

#### Course Difficulty

The course builds all the principles one learnt in ME 219: Fluid Mechanics (UG). It re-constructs the Bernoulii’s equation, statics, then moves to Reynolds transport theorem, and differential analysis of the Navier Stokes equations. Till the mid-sem, everything is a repetition of ME219, and hence ‘easy’ in the ideal sense. The later part is tougher than ME219 per se, as it covers more advanced topics, such as vorticity dynamics, LES/RANS modeling of Navier Stokes equations. I particularly don’t think the student will feel this course as difficult if they performed decently in ME219. I would rate it a 7/10 in terms of difficulty.

#### Time Commitment Required

The classes are worth 3 hours per week. There were a total of 5 assignments in the course, with a week to complete them, and around 7-10 questions in each assignment based on the previous set of lectures. Ideally should take 4-5 hours in those weeks to complete the assignments. The questions are moderately tough for most part, and only require ‘minimal’ thinking. However, they are lengthy. Some questions are interesting, and require thinking, but are very few. So 4-5 hours, 5 times a semester is enough for the assignments. For regular reading, I would say devoting 2 hours a week should be more than enough if the student listens to the lectures properly.

#### Grading

In 2019, 1 AA was awarded (to the highest scorer), and relative to his/her score, the other grades were allotted. 4 AB’s was allotted, and a similar number of BB’s in a total of nearly 30 students. I would say it’s not the chillest courses in grading, but not the worst either. The highest course total was around 75/100, and the mean was around 45-50/100

#### Attendance Policy

No attendance policy. However, there are 2 surprise quizzes, one pre-mid sem and one post-midsem, combined weightage of 5-10%. The pre-mid sem quiz should be relatively easy for everyone as it is a repetition of ME219. The post-mid sem quiz requires the student to have some knowledge of the material covered in lectures. Overall, moderately tough. The quizzes were both conducted near the mid sem/end sem week

#### Pre-requisites

ME 219 is mandatory in the sense it’s an odd sem course, to be completed in 3rd semester, and this course runs in the even semester. So the earliest opportunity to do it is 4th semester. Prof. Ranjan only asks that you have a basic understanding of vector calculus, and fluid mechanics.

#### Evaluation Scheme and Weightage

5-10% surprise quizzes (2 quizzes), 25% mid sem, 25%end sem, 5-10% assignments, rest: course project-there was a list of simple real-life fluid mechanics topics provided by the instructor. The students had to form a group of a maximum of 4 people, and prepare a 15 minute presentation on it. On the day of the presentation, any one of the 4 members could be asked to present based on a ‘lucky draw’. The topics were fairly easy to google and find information from. Overall, an extremely easy way to gather a few marks in this course

#### Topics Covered in the Course

ME219 + vorticity dynamics, statistical methods in turbulence, RANS/LES modeling of turbulent flows, external flows + tensor algebra

#### Mechanism of Instruction and Teaching Style

Slides and traditional blackboard teaching. The slides are however not enough, in the later parts of the course, and require that the student has good notes of what Prof. Ranjan writes on the board. He takes regular feedback on the course content and teaching from everyone, to adapt his teaching method, which makes him a good ‘teacher’. He cares about the student’s learning, and provides practical demonstrations of certain concepts through small real-life experiments. He’s always happy to help outside the lectures and easily available on mail. So overall, the instruction method is much better than a lot of courses.

#### Assignments and projects in the Course

5 easy to moderate assignments. Project as described above.

#### Exams

2 surprise quizzes:moderately easy, mid-sem and end-sem: We had ample time to complete the paper. There were a few easy questions straight from the assignments. A few moderately tough questions which involved some thinking and lengthy calculations were there too. The average of the paper used to be around 50% marks.

#### References

- Kundu and Cohen, Fluid mechanics
- G.K. Batchelor, Fluid dynamics
- Stephen Pope, Turbulent flows However, Kundu and Cohen is the primary textbook, and sometimes the questions are straight from its examples. The students will need to read this book at least once to understand the concepts. This reference book is used all across the top universities in the world for their fluid mechanics courses, and provides a really competitive understanding of the subject. It is a more involved text than the ones used in ME 219, and in general provides a more fundamental understanding.

#### Importance of Course

ME 651 builds a deeper understanding of fluid dynamics than ME 219. Since it involves the use of tensor algebra, the course equips the student to more or less understand all kinds of nonlinear equations in other mechanical engineering courses. Having a decent understanding of the course can allow the student to pick up more advanced courses in TFE such as Turbulence, Biofluid dynamics, CFD, MHD etc and pursue research under professors in the field etc. In this sense, the course opens a lot of opportunities.

#### Other Interesting Links

Useful videos of the course can be found on YouTube, and a teaching aid software provided by Prof. Ranjan.