NORTHEASTERN UNIVERSITYDepartment of Chemical EngineeringCHME 2311 Transport 1 Laboratory September x, 2016
TO: Nassim AnnabiFROM: Ahmed Alhosani, Timothy OrthSUBJECT: Effects of Different Fluids and Temperatures on Viscosity
Summary
This report provides an analysis and comparison of the results of different fluids,
temperatures, and two different approaches for finding viscosity. More specifically the three
different fluids included water, salt water, and water cornstarch mixture, the temperatures effect
was tested at 25 , 40 and 55 , lastly the two different approached were the ball drop ℃ ℃ ℃approach and viscometer approach. For each variable we repeated the trials three times in order
to improve the accuracy and precision of our results. Firstly ball drop method, the ball was
dropped in the graduated cylinder filled with a fluid three times at each temperature 25 , 40 ℃ ℃and 55 , a total of nine times for each fluid. Recorded data included height, time taken, radius ℃of the ball, from these recorded data density, velocity of the ball and viscosity were calculated.
Secondly Brookfield viscometer method, the Brookfield Viscometer’s spindle was placed in the
fluid, the reading displayed on the viscometer was recorded, and it was repeated three times at
each temperature for every solution.
Through the experimental procedure followed to measure viscosity of the three fluids,
water, salt water, and water cornstarch mixture. The results of viscosities for the ball drop
method were as follows, for water as temperature increased from 25C to 40C, the viscosity of the
fluid decreased from 2.43 kgms to2.09 kg
ms , the same relation was observed with salt water, where
the viscosity decreased but slightly less compared to water from 2.675 kgms to 2.59 kg
ms . For our
non-Newtonian fluid the opposite relationship was observed, the viscosity increased from
529.2 kgms to782.66 kg
ms . The viscometer method results also confirmed the relationship that as
temperature increases, viscosity decreases for water and saltwater fluids, and increases for water
cornstarch mixture.
Introduction
The study of fluids is a very wide science focusing mainly on the behavior of gases or
liquids at motion or static, fluid is defined as a liquid or gas that deforms continuously when
acted on by a shearing stress.(2) Viscosity is a characteristic used to describe a fluid and can be
defined as a quantitative measure of the fluid resistance to flow, more specifically it measures the
fluid strain rate that is formed from an applied shear stress, or to be more concise is describes the
fluidity of a liquid. (1) The main purpose of this experiment was to understand and measure the
effect of three different variables, which different three fluids, changes in temperature and two
different methods of measurement on viscosity. The two methods were the ball drop method and
viscometer method, the ball drop method was based on the idea of measuring fluid viscosity by
an object moving through that specific fluid. Viscometer method was based on the idea mainly of
measuring the fluid viscosity by a moving surface in interaction with a specific fluid.
Fluid viscosity has many practical applications in real life, which are extremely
important. The most popular application is the paint industry, its used almost entirely everywhere
from painting buildings, walls, computers, planes, drawing pictures, etc. The viscosity of the
paint is a very important factor to consider, it has to do mostly with the paints resistance, whether
it can be applied with a roller, brush, a sprayer or other means. (4) The viscosity of the paint can
be measured in several ways, special engineered dip or flow cups that measure the efflux time of
the fluid, the time required for a fluid to flow out. (5) The viscosity of the paint is an indicator for
the paints intended use to be as efficient and effective as possible, a thicker paint is used for
drawing work as its thickness resists flowing, a thinner paint is used for automotive and interior
paintings of the walls. (4)
Viscosity is a variable that vary as a function of temperature and pressure, but pressure is
considered to be extremely less effective compared to temperature, which is the main factor
affecting viscosity. In general for liquids as the temperature increases, the viscosity decreases
and in gases as the temperature increases, the viscosity also increases. (1) In a liquid which is our
main focus, the cohesive forces and molecular interaction affect the liquid viscosity, at room
temperature the molecules are strongly bonded together by attractive molecular forces and these
forces causes viscosity, because it is difficult for individual molecules to move because of the
attractive forces. As a temperature increases, the kinetic energy increases which makes the
molecules become more movable, which is because the molecular attractive forces decreases
thus viscosity decreases.(6)
The main objective of this experiment was to measure the effect of three variables on
viscosity. Firstly temperature at 25C, 45C and 55C, secondly three different fluids, which were
water, saltwater and water cornstarch mixture, thirdly two different methods of measurement,
which were viscometer method and ball drop method.
Methods
Initially all the safety measures were taken in case of any unexpected accident occurs, by
wearing the helmet and googles during the whole experiment period. Then all of the required
materials and equipment’s were gathered and placed on the table, materials included four 250mL
beakers, salt, cornstarch, and water. Equipment’s used were two Faithful SH-2 magnetic stirrer
(hot plate), one plastic graduated cylinders-polycarbonate, balance, two thermometers, one ball
and Brookfield viscometer. The solutions were prepared by weighing 50g salt and 100g of
cornstarch, then mixing them each with 200mL of water in 250mL beakers.
First fluid tested was water, water was poured into the graduated cylinder, then the ball
was dropped and the time taken was recorded by taking videos of the ball motion, since it was
too fast to use a stop watch. It was repeated three times at 25C, then the fluid was poured back
into the beaker so it can be used by the viscometer method, the appropriate viscometer spindle
was placed in the fluid to measure the viscosity, three measurements were taken from reader
displayed at the viscometer at 25C. Then the beaker is placed in the hot plate to raise the
temperature to 45C, a thermometer was used to monitor the change in temperature.
Simultaneously as we waited for water to heat the same procedure were followed for our second
fluid saltwater and measurements were taken. As soon as the temperature desired for water is
reached, we tested the fluid as fast as possible because we didn’t want the temperature to drop
from our wanted temperature, the same procedures were repeated at 55C. For our water
cornstarch mixture, we faced the problem of getting the right ratio of water and cornstarch to
make Oobleck a non-Newtonian fluid. Using our previous ratio, the mixture was light as water,
so we kept water constant then kept adding starch till the fluid became thick, the same procedure
was then followed for our water cornstarch mixture. We had a total of 27 measurements for each
method used, other measurements included the radius, density, mass of ball and the heights of
the cylinder filled with different fluids.
Results
All of the raw data can be found in the appendix. This experiment uses drop ball and
viscometer method for measurements, the main goal was to observe the effect of different
intervals of temperature and different fluids on viscosity. For the ball drop method, the velocity
was measured by the following formula
v=ht (Eq.1),
h= height of fluid filled in graduated cylinder (m),
t time taken (s)
Then viscosity was calculated by the following formula
μ= (4/9)(r2g(ⲣs-ⲣf))/(V) (Eq.2),
where r = radius of ball (m) , g = acceleration due to gravity(m/s2) , ⲣs = density of ball(kg/m3) ,
ⲣf = density of fluid(kg/m3), V= velocity of ball (m/s).
Table 1. Effect of temperature on viscosity
Ball Drop Method Time 1 (s) Time 2 (s) Time 3 (s) Average Time(s) Viscosity(Kg
/ms)
Water (25 )℃ 0.41 0.47 0.5 0.46 2.435347022
Water (55 )℃ 0.47 0.35 0.3 0.373333333 1.976513525
Saltwater (25 )℃ 0.43 0.5 0.83 0.586666667 2.675288688
Saltwater (55 )℃ 0.45 0.7 0.56 0.57 2.599286168
Cornstarch-water
(25 )℃61 66 63 63.33333333 529.2032019
Cornstarch-water
(55 )℃90 94 97 93.66666667 782.6636829
Viscometer
Method
Viscosity 1 (cP) Viscosity 2
(cP)
Viscosity 3
(cP)
Average
Viscosity(cP)
Water (25 )℃ 0.75 1 1 0.916666667
Water (55 )℃ 0.75 0.5 0.5 0.583333333
Saltwater (25 )℃ 0 0.5 0.75 0.416666667
Saltwater (55 )℃ 0.25 0.5 0.25 0.333333333
Cornstarch-water
(25 )℃362.5 375 375 370.8333333
Cornstarch-water
(55 )℃950 975 1000 975
Table 1 represents the effect of increasing temperature on viscosity. The results from both
methods shows that for water and salt water as the temperature increases, the viscosity of fluid
decreases. So our result agrees with the theory that for liquid fluids, the viscosity and
temperature are inversely related. This is because the increase in temperature leads to an increase
in the thermal energy, which at the molecular level helps the molecules to be more mobile, since
the attractive energy is reduced thus the viscosity of the fluid decreases.(6) Our non-Newtonian
fluid Oobleck had a direct relationship were as the temperature increases the viscosity increases,
this could be due to the fact that it is not a Newtonian fluid, so its viscosity will be a function of
the shear rate and should behave completely differently.(2) Table 2 represents viscosities values
of the three fluids at the same temperature from the two methods, the results shows that the
viscosity of water and saltwater are so close to other, thus their flowing properties will be
similar, the viscosity of water cornstarch mixture was found to be extremely high compared to
the other two fluids. Figure 1 shows a comparison between the results of the two methods, during
the experiment we deduced that for a non-Newtonian fluid like Oobleck a ball drop method is
not the best method to measure its viscosity, firstly because the fluid was extremely thick and it
was difficult to get the ball for another trials and even observe it as it falls, a viscometer method
would be more efficient method.
Table 2. Effect of different fluids on viscosity
Ball Drop
Method
Average
Time(s)
Velocity(m/s) Viscosity(Kg/ms)
Water (25 )℃ 0.46 0.42103260 2.4353470
Saltwater
(25 )℃0.58666666 0.37883522 2.6752886
Cornstarch-
water (25 )℃63.3333333 0.00172452 529.20320
Viscometer
Method
Viscosity
1 (cP)
Viscosity 2 (cP) Viscosity 3 (cP) Average
Viscosity
Water (25 )℃ 0.75 1 1 0.9166666
Saltwater
(25 )℃0 0.5 0.75 0.4166666
Cornstarch-
water (25 )℃362.5 375 375 370.8333
Water (25 )℃
Water (40 )℃
Water (55 )℃
Saltwater (25 )℃
Saltwater (40 )℃
Saltwater (55 )℃
0
0.5
1
1.5
2
2.5
3
Ball drop vs. Viscometer method
Viscometer Method Gravitational Method
Visc
osity
Figure 1. Comparison of viscometer and ball drop method
Conclusion and Recommendations
In this experiment three variables were studied and compared, it can be concluded firstly
that the viscosity is a function of temperature and that temperature in liquids for Newtonian
fluids have an inverse relationship, whereas temperature increase, viscosity decreases. For our
non-Newtonian fluid Oobleck it was observed that there was a direct relationship between the
temperature and viscosity. Secondly it was concluded from comparing the two methods of
measuring viscosity, both of them were effective and efficient but in case of a non-Newtonian
fluid like Oobleck drop ball method is not favored. Recommendations would be to choose a new
variable that would replace one of the two variables either effect of different fluids or two
different methods, that could explain and clarify viscosity same as the temperature variable.
Another recommendation would be to do some experiment of studying viscosity that has a use
real use in the world.
References
1. Brian Michael Godfrey, "EXPERIMENTAL RESULTS FOR VISCOSITY MEASUREMENTS PERFORMED ON THE INTERNATIONAL SPACE STATION USING DROP COALESCENCE IN MICROGRAVITY" , 8-2011
2. Bruce Roy Munson, ”Fundamental of Fluid Mechanics”, 8th ed, 19903. Ping Yuan*, Ben-Yuan Lin, Syu-Fang Liu, “ Measurement of viscosity in a vertical
falling ball viscometer” , 2007 4. The House Painting, “Paint Viscosity: A Look at the Basics”, June 10,2013 ,
http://www.housepaintingguide.org/paint-viscosity-a-look-at-the-basics/ 5. Byk instruments, “ An Introduction to Measuring Viscosity For The Paint Industry”,
https://www.azom.com/article.aspx?ArticleID=10630 , February 4, 2014 6. Azo Materials, “How does Temperature Change Viscosity in Liquids and Gases?”,
https://www.azom.com/article.aspx?ArticleID=10036 , September 23,2013
Appendix
Broader Impacts
Viscosity is a quantity expressing how much a fluid would try to resist a flow, which can be classified into two type’s Newtonian and non-Newtonian fluid. The different types of non-Newtonian fluid can be differentiated by how their apparent viscosity changes with shear rate. As a team we plan on using the knowledge we learned in this experiment about viscosity specifically to help us in our next project.
Material list
Equipment Specifications Drawing
Balance Operating temperature between 10 and 40C.Capacity: 1200g * 0.01g
Brookfield SYNCHRO-LECTRIC VISCOMETER
For fluids that range from 8,000-64,000 cps.
Plastic graduated cylinders-Polycarbonate
one 250ml
Faithful SH-2 MAGNETIC STIRRER (hot plate)
Max. Temp: 380Max.Volume: 2000 mL
Water from faucet 200-250 mL
Thermometer
Salt
Corn Starch : 400g for Brookfield Viscometer, 350g for falling ball
Cost Analysis
Cornstarch $2.51Salt $2.09250 mL beaker $38.49Thermometer $3Hot plate $280Balance $310
Safety Analysis
Personal Safety
Insulated gloves were used when moving the heated solutions, also hard hats and goggles are worn during the whole experiment time.
Material Safety
Materials used were no toxic. The cornstarch-water mixture must be thrown away in the garbage because it could clog the plumbing if poured down the drain. The only danger is the heat used- if any of the solutions at 40 or 55 gets in contact with skin that could lead to burns ℃ ℃
Equipment Safety
The Brookfield Viscometer used can operate between -20 and 65 . None of the solutions ℃ ℃will react with the spindles, graduated cylinders. The hot plate, balance, and viscometer all use electricity, so the only potential electrical hazards would be because of a serious malfunction in those pieces of equipment. The electrical shut-off switch can be used in an emergency to cut all power to the experiment.
Safety check in/out sheet
Procedure
Gravitational Method
First, prepare solutions of saltwater, and cornstarch-water. This will be done by mixing 50g salt, and 100g cornstarch with 200 mL of water each. Second, these solutions will be put into 250 mL graduated cylinders, and their height will be measured and written down. Third, a marble will be massed. Fourth, the marble will be dropped through each solution three times, and the time it takes to reach the bottom will be recorded. This will be repeated nine times for each solution: three times at 25 , three times at 40 , and three times at 55 .℃ ℃ ℃
Brookfield Method
First, the solutions will be prepared for use with the Brookfield Viscometer. If more than 200 mL of each solution is needed, then 400 mL of each solution will be prepared using the same mass and volume ratios of the original solutions. Second, the viscosity of each of these solutions will be measured by placing the Brookfield Viscometer’s spindle in the solution, and recording the reading displayed on the viscometer. This will be done nine times for each solution: three times at 25 , three times at 40 , and three times at 55 .℃ ℃ ℃
Timeline:
Taking safety measuresPreparing the mixturesUsing the ball drop methodThen viscometer methodThen heatRepeat the same stepsFinished around4:40 PM
Raw Data
Gravitational Method
Height (m)
Radius of the Sphere (m)
Density of the Sphere (kg/m^3)
Time 1 (s)
Time 2 (s)
Time 3 (s)
Average Time(s)
Velocity(m/s)
Viscosity(Kg/ms)
Water (25 )℃
0.193675
0.00953
3592.15
0.41
0.47
0.5 0.46 0.421032609
2.435347022
Water (40 )℃
0.193675
0.00953
3592.15
0.39
0.31
0.45
0.383333333
0.50523913
2.029455852
Water (55 )℃
0.193675
0.00953
3592.15
0.47
0.35
0.3 0.373333333
0.518772321
1.976513525
Saltwater (25 )℃
0.22225
0.00953
3592.15
0.43
0.5 0.83
0.586666667
0.378835227
2.675288688
Saltwater (40 )℃
0.22225
0.00953
3592.15
0.31
0.63
0.47
0.47 0.47287234
2.143271051
Saltwater (55 )℃
0.22225
0.00953
3592.15
0.45
0.7 0.56
0.57 0.389912281
2.599286168
Cornstarch-water (25 )℃
0.10922
0.00953
3592.15
61 66 63 63.33333333
0.001724526
529.2032019
Cornstarch-water (40 )℃
0.10922
0.00953
3592.15
70 78 73 73.66666667
0.001482624
615.5468822
Cornstarch-water (55 )℃
0.10922
0.00953
3592.15
90 94 97 93.66666667
0.00116605
782.6636829
Viscometer Method
Viscosity 1 (cP)
Viscosity 2 (cP)
Viscosity 3 (cP)
Average Viscosity(cP)
Water (25 )℃ 0.75 1 1 0.916666667
Water (40 )℃ 0.75 1 0.75 0.833333333
Water (55 )℃ 0.75 0.5 0.5 0.583333333
Saltwater (25 )℃
0 0.5 0.75 0.416666667
Saltwater (40 )℃
0.5 0.5 0.25 0.416666667
Saltwater (55 )℃
0.25 0.5 0.25 0.333333333
Cornstarch-water (25 )℃
362.5 375 375 370.8333333
Cornstarch-water (40 )℃
3625 3012.5 3125 3254.166667
Cornstarch-water (55 )℃
950 975 1000 975
