Who Was Osborne Reynolds?

by David E. Schwartz

In my research I came across the work of Osborne Reynolds, a 19^th century English physicist and engineer whose area of interest was "turbulence" (fluid mechanics). In 1883 Reynolds, by experimenting with pipes of varying sizes, was able to come up with a number, (now known as the "Reynolds number") that tells engineers when a fluid system will reach turbulence.

The Reynolds number is calculated by multiplying together several variables including the diameter of the pipe, the velocity of flow, the mass of the fluid, and the fluid’s viscosity. Reynolds showed that when that magic number is reached, the flow through the pipe becomes turbulent (i.e. becomes erratic).

 So, what does this have to do with horse racing? Plenty. Especially if you are a modeler. Suppose you are modeling 6 furlong races at Hollywood Park for 3 factors…

 How would you interpret this model? This is the kind of model that one would call "loose." There is no single factor that can be used to eliminate down to a playable number of horses, though when we sum the columns we can come up with "something."

 Let’s create some "Reynolds number" columns for each 2-factor combination. Thus, the EPxSP for race 4 is 12 because 3 x 4 =12 (i.e. EP x SP = EPxSP). 

Now when we look at the worst, it makes more sense. SP x CL is certainly the most powerful column, as no winner has had an SPxCL Reynolds of worse than 5! It also explains why, if class is so important, a horse with a Class rank of 5 could win (race 8). He made it up by having 1’s in both of the other two columns!

If we were to describe the profile of a winner in these 8 races, we could say:

1. Must have a 4 or less in EP.

2. Must have a 4 or less in SP.

3. Must have an SPxCL of 5 or less.

4. Must have an EpxSP of 6 or less.

Applying rule #1 eliminates #5, leaving: #1 #2 #3 #4 (not enough EP)

Applying rule #2 eliminates #4, leaving: #1 #2 #3 (not enough SP)

Applying rule #3 eliminates #1 & #3, leaving: #2 (not enough SP and CL in combination)

The Reynolds number will also help when you have a model that is a little more obvious. Let’s add one more column: EpxSPxCL.

The rules for this race are:

1. Must have 3 or less in SP

2. Must have 3 or less in CL.

3. Must have 4 or less in SPxCL.

4. Must have 8 or less in EpxSPxCL.

Once again, with conventional modeling we would not have been able to eliminate as many horses. The first two steps would have easily gotten us down to two, but the model clearly says that a horse must have enough of everything (i.e. EPxSPxCL) to qualify.

Think about that minimum in rule #4. How does a horse get 8 or less?

Let’s work up a set of descriptions.

• If a horse has 2 or more 1’s, he’s in.

• If he has only a single 1, he must have no worse than 2 x 3 in the other two slots.

• If he has no 1’s, he must be all 2’s.

• All other horses are out!

We'll revisit Osborne Reynolds and his contributions to handicapping at a later time.