# Relationship between flow rate and viscosity of oil

started. Motor oils are manufactured with a variety of viscosity values to suit weather . The mass-to-volume ratio is the relationship between mass and volume. Grease is more viscous than engine oils. • Liquids are In liquids the viscosity is due to the cohesive forces between equation are called newtonian fluids and η = constant independent of When η does depend upon the velocity of flow the. Therefore, viscosity has a profound effect on the flow rate: m Re the relation between viscosity and shear rate, fluids can be classified as Newtonian and.

Once this shear stress is removed the paint returns to its resting viscosity, which is so large that an appropriately thin layer behaves more like a solid than a liquid and the paint does not run or drip. Think about what it would be like to paint with water or honey for comparison.

## The Effect of Flow Rate and Viscosity on Oil Filter Performance

The former is always too runny and the latter is always too sticky. Toothpaste is another example of a material whose viscosity decreases under stress.

Toothpaste behaves like a solid while it sits at rest inside the tube. It will not flow out spontaneously when the cap is removed, but it will flow out when you put the squeeze on it.

Now it ceases to behave like a solid and starts to act like a thick liquid. You don't have to worry about it flowing off the brush as you raise it to your mouth. Shear-thinning fluids can be classified into one of three general groups.

### The Effect of Flow Rate and Viscosity on Oil Filter Performance

A material that has a viscosity that decreases under shear stress but stays constant over time is said to be pseudoplastic. A material that has a viscosity that decreases under shear stress and then continues to decrease with time is said to be thixotropic.

If the transition from high viscosity nearly semisolid to low viscosity essentially liquid takes place only after the shear stress exceeds some minimum value, the material is said to be a bingham plastic.

Materials that thicken when worked or agitated are called shear-thickening fluids.

An example that is often shown in science classrooms is a paste made of cornstarch and water mixed in the correct proportions. The resulting bizarre goo behaves like a liquid when squeezed slowly and an elastic solid when squeezed rapidly. Ambitious science demonstrators have filled tanks with the stuff and then run across it.

As long as they move quickly the surface acts like a block of solid rubber, but the instant they stop moving the paste behaves like a liquid and the demonstrator winds up taking a cornstarch bath.

### The Importance of an Oil's Viscosity

The shear-thickening behavior makes it a difficult bath to get out of. The harder you work to get out, the harder the material pulls you back in. The only way to escape it is to move slowly. Laboratories are allowed to choose any of the three conditions to help in establishing a convenient test time.

However, the standard procedure will state that for comparison of filter performance, the comparison should be done at the same test condition. With respect to viscosity effects on beta, we have found that the efficiency is generally not highly affected unless the viscosity ranges are extreme I'm beginning to sound like a broken record.

I did a study at Oklahoma State University many years ago on this effect and found that dirt holding capacity was affected, generally decreasing, as viscosity was increased. Such studies were run on the same oil while viscosity was adjusted by changing temperature.

In such case, we have found a difference in filter performance, which we attribute to both viscosity effects as well as the influence of other fluid properties, including additives, conductivity, etc.

We are currently extending this work to include operating conditions from typical field applications to help us be better able to predict how a filter will perform in a specific field application with operating conditions and oils which are different from the "mild" laboratory multi-pass test. We know that field performance of filters cannot be directly correlated to laboratory multi-pass test results as actual field systems often have different oils, variable flow, pressure surges, temperature cycling, vibration, and a much lower ingression rate than the lab test.

The research we are currently conducting will give us better insight into correlating lab test results to actual field performance. We hope to have something published on this within this year.

Effects of Temperature on Viscosity and Flow Rate of Vegetable Oil

Bensch's comments to Joel White's questions are very timely.