Dual solutions for unsteady boundary layer flow of nanofluids over stretching/shrinking surfaces and stability analysis
There are five unsteady boundary layer flow problems being considered which involved the regular flow, rotating boundary layer flow, the stagnation-point flow over a linear and an exponential stretching/shrinking surface which the flows pass through a flat or a cylindrical surfaces. Besides, the...
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/83663/1/FS%202019%2019%20-%20IR.pdf http://psasir.upm.edu.my/id/eprint/83663/ |
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| Summary: | There are five unsteady boundary layer flow problems being considered which
involved the regular flow, rotating boundary layer flow, the stagnation-point flow
over a linear and an exponential stretching/shrinking surface which the flows pass
through a flat or a cylindrical surfaces. Besides, the effects such as constant mass
flux, velocity slip, Soret and Dufour are also taken into account. The mathematical
models for boundary layer problems by considering different nanoparticles namely
Copper, Alumina and Titania are dispersed into the water. The nanofluid model by
Tiwari and Das are used to study the effect of nanoparticle volume fraction towards
the flow and heat transfer behaviors at the surface. The governing equations in the
form of partial differential equations are transformed to the ordinary differential
equation using the similarity variables and is solved by using bvp4c function in
Matlab software to gain the numerical results which focused on obtaining the dual
solutions so that the stability analysis can be performed.
The results have shown the dual solutions existed for unsteady accelerating and decelerating
flow with the presence of mass suction effect within a certain range of
stretching and shrinking surfaces. Increasing the rotation effect, nanoparticle volume
fraction, considering different nanoparticles and exponential stretching/shrinking
surface is proven can enlarge the range of solutions. Considering Copper-water
has resulted in increasing the skin friction coefficient and heat transfer rate at the
surface. Performing the stability analysis has found that the first solution is stable
solution meanwhile the second solution is unstable solution. |
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