# Demonstration of Effect of Viscosity on Flow in Thin Enclosure

## Poster Number

Table by entrance

Department of Mechanical Engineering

Faculty

## Introduction/Abstract

Fluid dynamics, which studies liquids and gases and their interactions with objects around them, has many applications in our way of life - from designing water supply line to transportation vehicles to atmospheric science. An important tool to study fluid dynamics is flow visualization, which aids to show details of a given flow. In the present work, I have developed a simple flow visualization device to demonstrate how viscosity of glycerin-water mixture affects its flow in a thin enclosure. It is shown viscosity of the mixture is highly nonlinear with respect to percentage of the two liquids in the mixture. Furthermore, other fluid dynamics behaviors such as meandering is exhibited. The demonstration is applicable to physics as well as fluid dynamics courses, as a tool for enhancing lectures.

## Purpose

Viscosity is a fluid property that is important in studying fluid dynamics problems. In teaching fluid dynamics, it is desirable to have demonstration devices to exhibit fluid properties and how they affect a given flow. Therefore, in the present work, the goal was to design a device to show the effect of viscosity on the flow of glycerin-water mixture. Glycerin viscosity is approximately 1000 times the viscosity of water. Since glycerin is easily mixed with water, a mixture of glycerin-water can have a viscosity between that of glycerin down to that of water - a three-fold in order of magnitude - depending on the percentages of the liquids used in the mixture.

## Method

To have a practical demonstration device, the present design utilizes a thin enclosure made of acrylic to make a sealed, stand alone and portable device that contains equal volumes of glycerin-water mixture and air. To add to the visual effect, three partial partitions are included in the middle of the enclosure to separate the the mixture from the air. Five identical enclosures were made, each to contain different percentage of glycerin-water mixture. The five percentages used are: 0, 25, 50, 75, and 100. The demonstration is qualitative in nature.

## Results

When the enclosures are turned upside down, the mixture flows down due to gravity. The flow of 100% glycerin (0% water) is extremely slow, while the flow of 0% glycerin (100% water) is extremely fast. However, what is surprising is that addition of water drastically changes the viscosity of the mixture; it lowers it nonlinearly. For example, the flow behavior of 100% water and 75% water-25% glycerin are very close.

## Significance

The enclosures provide demonstrations of viscosity effect on flow of glycerin-water mixture. The demonstration devices are simple, self-contained, and require no power to operate. They are portable and can be reused without waiting or cleaning. Most importantly, they exhibit nonlinearity of viscosity with respect to the percentage of the components in the mixture. As a bonus, the demonstrations are visually engaged, and as such they are accessible to everyone, regardless of age or science background.

## Location

Library and Learning Center, 3601 Pacific Ave., Stockton, CA 95211

## Format

Poster Presentation

## Share

COinS

Apr 29th, 10:00 AM Apr 29th, 12:00 PM

Demonstration of Effect of Viscosity on Flow in Thin Enclosure

Library and Learning Center, 3601 Pacific Ave., Stockton, CA 95211

Fluid dynamics, which studies liquids and gases and their interactions with objects around them, has many applications in our way of life - from designing water supply line to transportation vehicles to atmospheric science. An important tool to study fluid dynamics is flow visualization, which aids to show details of a given flow. In the present work, I have developed a simple flow visualization device to demonstrate how viscosity of glycerin-water mixture affects its flow in a thin enclosure. It is shown viscosity of the mixture is highly nonlinear with respect to percentage of the two liquids in the mixture. Furthermore, other fluid dynamics behaviors such as meandering is exhibited. The demonstration is applicable to physics as well as fluid dynamics courses, as a tool for enhancing lectures.