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You searched for subject:(Collocated Grid). Showing records 1 – 2 of 2 total matches.

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Texas A&M University

1. Roy, Pratanu. Numerical Study of Flow and Heat Transfer in Rotating Microchannels.

Degree: 2014, Texas A&M University

Investigation of fluid flow and heat transfer in rotating microchannels is important for centrifugal microfluidics, which has emerged as an advanced technique in biomedical applications and chemical separations. The centrifugal force and the Coriolis force, arising as a consequence of the microchannel rotation, change the flow pattern significantly from the symmetric profile of a non-rotating channel. A successful design of a centrifugal microfluidic device depends on effectively regulating these forces in rotating microchannels. Although a large number of experimental studies have been performed in order to demonstrate the applications of centrifugal microfluidics in various fields, a systematic study on the effect of rotation, channel aspect ratio, and wall boundary conditions on the fluid flow and heat transfer phenomena in rotating microchannels has not yet been conducted. During the present study, pressure-based finite volume solvers in both staggered and collocated grids were developed to solve steady and unsteady, incompressible Navier-Stokes equations. The serial solver in collocated grid was parallelized using a Message Passing Interface (MPI) library. In order to accelerate the convergence of the collocated finite volume solver, a non-linear multi-grid method was developed. The parallel performances of the single and multi-grid solvers were tested on a two-dimensional lid driven cavity flow. High fidelity benchmark solution to a lid driven cavity flow problem in a 1024 x 1024 grid was presented for a range of Reynolds numbers. Parallel multigrid speedup as high as three orders of magnitude was achieved for low Reynolds number flows. In addition, the optimal multigrid efficiency was validated. The fluid flow in a rotating microchannel was modeled as a steady, laminar in compressible flow with no slip and slip boundary conditions. For no slip boundary condition, critical values of parameters that determine the extent of the centrifugal force and the Coriolis force were identified. The critical aspect ratio (=width/height) that causes the optimal mixing of two liquids was found to be 1.0. For liquid slip boundary condition, the effect of rotation on liquid slip flow in rotating microchannels with hydrophobic and superhydrophobic surfaces was studied. New correlations for friction relation (fRe) as a function of slip length (?) and rotational Reynolds number (Re?) were proposed. It was also found that, the liquid slip can increase or decrease the heat transfer depending on the secondary flow effect and the aspect ratio of the microchannel. The microscale effects, such as surface tension and contact angle boundary condition, were included in the modeled problem. A level set method was applied to incorporate these microscale effects, which will enable us to investigate the unsteady nature of the liquid meniscus during two-phase flow simulations. Advisors/Committee Members: Anand, N. K. (advisor), Banerjee, D. (advisor), Han, J. C. (committee member), Chen, H. C. (committee member).

Subjects/Keywords: Rotating Microchannels; Finite Volume Method; Multigrid Algorithm; Parallel Algorithm; Collocated Grid; Slip Boundary Condition; Level Set Method

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APA (6th Edition):

Roy, P. (2014). Numerical Study of Flow and Heat Transfer in Rotating Microchannels. (Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/153917

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Roy, Pratanu. “Numerical Study of Flow and Heat Transfer in Rotating Microchannels.” 2014. Thesis, Texas A&M University. Accessed January 21, 2020. http://hdl.handle.net/1969.1/153917.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Roy, Pratanu. “Numerical Study of Flow and Heat Transfer in Rotating Microchannels.” 2014. Web. 21 Jan 2020.

Vancouver:

Roy P. Numerical Study of Flow and Heat Transfer in Rotating Microchannels. [Internet] [Thesis]. Texas A&M University; 2014. [cited 2020 Jan 21]. Available from: http://hdl.handle.net/1969.1/153917.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Roy P. Numerical Study of Flow and Heat Transfer in Rotating Microchannels. [Thesis]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/153917

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Farrokhnejad, Mehdi. Numerical Modeling of Solidification Process and Prediction of Mechanical Properties in Magnesium Alloys.

Degree: 2013, University of Western Ontario

A formulation used to simulate the solidification process of magnesium alloys is developed based upon the volume averaged finite volume method on unstructured collocated grids. To derive equations, a non-zero volume fraction gradient has been considered and resulting additional terms are well reasoned. For discretization the most modern approximations for gradient and hessians are used and novelties outlined. Structure-properties correlations are incorporated into the in-house code and the proposed formulation is tested for a wedge-shaped magnesium alloy casting. While the results of this study show a good agreement with the experimental data, it was concluded that a better understanding of the boundary condition that existed during the experiment would result in a more agreeable result. A variety of boundary conditions are considered at the mold-casting interface to replicate the existing conditions during the casting process. The predicted cooling rates and experimental correlations are used to predict the local grain size and average yield strength. The grain size and thickness of the skin and core regions are taken into account to modify the local yield strength. Results are compared to previously reported experimental data. The outcome of this comparison emphasizes the importance of the influence of cooling rate on the mechanical properties of castings. The effect of different boundary conditions, which resulted in variation of the cooling rates, various grain sizes and, hence, various yield strengths are studied and discussed. It is concluded that the formulation and the numerical treatment presented in this work can be used as an excellent framework to capture the key features of the solidification process, and also provides sufficient microstructural information for estimating the local mechanical properties of die-cast components.

Subjects/Keywords: Solidification modeling; Magnesium alloys; Phase change modeling; Wedge casting; Die-Casting modeling; Volume-Averaged technique; Finite Volume Method; Unstructured grid; Collocated grid; Applied Mechanics; Engineering Mechanics; Manufacturing; Metallurgy; Structural Materials; Transport Phenomena

…41 Figure 2-3: A portion of the grid and related nomenclature used in the FVM… …53 Figure 2-4: Representative portion of a triangular unstructured grid for pressure… …75 Figure 3-1: A portion of the grid and related nomenclature used in the FVM… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Farrokhnejad, M. (2013). Numerical Modeling of Solidification Process and Prediction of Mechanical Properties in Magnesium Alloys. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/1459

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Farrokhnejad, Mehdi. “Numerical Modeling of Solidification Process and Prediction of Mechanical Properties in Magnesium Alloys.” 2013. Thesis, University of Western Ontario. Accessed January 21, 2020. https://ir.lib.uwo.ca/etd/1459.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Farrokhnejad, Mehdi. “Numerical Modeling of Solidification Process and Prediction of Mechanical Properties in Magnesium Alloys.” 2013. Web. 21 Jan 2020.

Vancouver:

Farrokhnejad M. Numerical Modeling of Solidification Process and Prediction of Mechanical Properties in Magnesium Alloys. [Internet] [Thesis]. University of Western Ontario; 2013. [cited 2020 Jan 21]. Available from: https://ir.lib.uwo.ca/etd/1459.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Farrokhnejad M. Numerical Modeling of Solidification Process and Prediction of Mechanical Properties in Magnesium Alloys. [Thesis]. University of Western Ontario; 2013. Available from: https://ir.lib.uwo.ca/etd/1459

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.