Physics 107: Living in a Fluid World (Jerry Gollub, )

Brief Description: An exploration of the role of fluid phenomena in nature and life, including:  The basic principles governing fluid motion; the functioning of organisms that live in fluids, or utilize fluids internally for circulation; and the role of fluid dynamics in understanding the weather and atmospheric phenomena.  Some phenomena that will be discussed during the course include:  how organisms adapt to take advantage of their local fluid environment; the diverse mechanisms they use to pump fluids; why the eyes of fish are not in the front; how insects walk on water and fly; why the atmosphere is cold at high altitudes; what determines the mean temperature of the earth, the physics of rain; how hurricanes work; and the predictability of the weather.

Further information:  Most of the universe is filled with fluids in motion.  We encounter fluid motion through the weather, through swimming and flight, and by observing the oceans.  Fluids are also essential for life:  organisms live in fluids, and fluids move inside of them.  In this course, we look at some of the basic properties of fluid motion, and apply them to both biological and physical situations.  In this way, we learn some physics, and we see how it gives insight into a great variety of natural phenomena.

Who should take this course:

            This course is intended primarily for students who are not majoring in the sciences, and are interested in the topic of the course.


            Some prior exposure to Newton’s laws of motion at the high school level would be helpful.

We will be expressing physical ideas in mathematical form.  I will need to assume basic skills in algebraic manipulation and quantitative reasoning, and a conceptual understanding of the basic ideas of integration and differentiation at the level of Math 113a.  Detailed mastery of calculus is not needed.  However, if you are strongly averse to quantitative reasoning and the use of mathematics, you might not enjoy the course. 


--For the first half of the course on biological fluid mechanics, we will use Steven Vogel, Life in Moving Fluids, a fine example of science writing that is accessible to non-specialists. 

--An excellent CD-ROM is recommended:  Multi-Media Fluid Mechanics CD-ROM, by G. M. Homsy, H. Aref, K. S. Breuer, S. Hochgreb, J. R. Koseff, B. R. Munson, (Cambridge University Press, 2000).

--Later in the course when we discuss atmospheric phenomena, I will provide written notes on Blackboard, and some articles.  I have so far been unable to locate a suitable textbook at the right level.  Most are too compendious for our needs.  However, I will put several texts on reserve, including:  Atmosphere, Weather, and Climate by Barry and Chorley, and The Atmosphere, by Lutgens and Tarbuck.

--Ed Lorenz, The Essence of Chaos, is recommended on the issue of atmospheric predictability, and may be assigned.

--Felice Frankel, The Design and Craft of the Science Image, should be useful for the photographic project, and will be available on reserve.  It provides wonderful advice  and examples for creating attractive and informative scientific images.

Additional objectives

--To understand some major ideas in physics and to see their wide applicability to phenomena involving fluid motion in varied contexts.

--To learn to use simple quantitative estimates and scaling ideas to evaluate scientific hypotheses.

--To appreciate the beauty of fluid flow phenomena, and to learn to capture it photographically.


For the first half of the course, we will follow the chapters in Vogel, and supplement his discussion of the physics concepts. 

Biofluid dynamics

What is a fluid?


The principle of continuity

Describing fluid flows: pathlines and streamlines

The velocity field

Pressure and momentum: Bernouilli

Drag and forces on organisms

The Reynolds number

Velocity gradients and boundary layers

Lift, flying, and swimming

Flows inside organisms

Very low Reynolds number flows (small organisms)

Changing flows

Interfaces and waves


Atmospheric phenomena

Temperature and Pressure in the Atmosphere

Radiation and the determinants of climate

Physics of clouds                                                                                (continued)

Waves in the atmosphere                                            

Atmospheric motions

Chaos and the predictability of the weather

Course requirements

            I ask for serious engagement by all participants.  This means:  coming to class reliably, doing the assigned readings and homework in a timely manner, and participating in class discussions and occasional laboratories to the extent that the size of the class allows.

            1.         Regular class attendance.  It is important that you come to all classes in order to profit adequately from this course and to fulfill your responsibilities as a participant.  You are expected not to miss more than two classes for any reason (including athletic events, oversleeping, etc.), other than illness.  If you anticipate difficulty in meeting this requirement, please do not take the course.

            2.         Readings and assignments.  You are expected to do the assigned readings and about 8 brief written assignments.  You are responsible for reviewing the sample solutions, which will be posted in the Science Library and on Blackboard.  I hope to arrange “help sessions” staffed by one or two physics majors.

            3.         A midterm exam and a final exam.  Review questions will be provided to guide your studying.

            4.         One laboratory session, to be arranged.  Here, you will explore a variety of fluid flows qualitatively. You may return to use these flows for #5 below.

            5.         A photographic project, in which you will take digital photographs of one or two fluid flows of your choice, attempt to explain the phenomena you observe, and organize your photographs into a Powerpoint poster presentation. 

            6.         (Alternative to #5) A short library research paper on a topic of your choice related to the course.


            The average course grade is typically around 3.2 in a course of this type, depending somewhat on class performance.  The following weights will apply to the various components of your work: 

                        Weekly assignments                                        25%                            

                        Two exams                                                      50%                            

                        Project or short paper                                     25%                            

            Homework assignments are expected on time, except in case of illness.  You may also have one no-penalty extension for up to a week in case you are swamped with work due simultaneously in different courses.  Just turn in a note in place of the assignment indicating that you wish to take a “free extension”.  Otherwise, the late penalty is 20% of the earned grade for up to 1 week.  Beyond that, it is still worthwhile to turn in late homework for about half credit.  (You will benefit from staying up to date.) It is permissible when working for half credit to refer to the posted solutions for ideas, but not to copy the solutions.

            I know from experience that students can’t master the material without coming to class regularly.  Therefore, absences (for reasons other than illness) will lead to a grade point penalty of about 0.1 grade point per absence if more than two were noted.  In extreme cases, a student may be dropped from the course or given an incomplete.

Honor code

            Students sometimes find it helpful to discuss homework together.  This is encouraged, but your written work should be your own and should not be copied from that of a study partner.  Two assignments that have substantially identical wording or equations would be presumed in violation of the honor code.  Assistance and sources must be acknowledged.

Interacting with Jerry Gollub

            Electronic mail (sent to jgollub) is always welcome and is the best way to reach me outside of class time.  I will usually reply within a day or so (less on weekday afternoons).  I will occasionally send you mail and announcements. 

            Phone: You may phone my office at 896-1196.  Please leave a message if I'm not there, along with your number and a suggested time in the evening when I can return your call. 

            Office:   I have found that the best way to get together is to arrange (after class) a mutually agreeable time.  You are also welcome to drop in (KINSC L109); afternoons are best.  Please do not hesitate to contact me; no question or topic is too small.  If you are having a lot of trouble with the homework, be sure to come to see me as soon as possible. 

            Feedback:  If you have concerns about the course, or ideas about how to make it better, you should let the me know immediately, either in person or by e-mail.  Don't wait!