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Entropy-stable residual distribution methods for unsteady scalar equations

Entropy-stable residual distribution methods for unsteady scalar equations / Sang Jit Chern
Penaburan sisa-sisa merupakan sejenis skema di dalam komputasi dinamik benda alir. Skema ini menggunakan kaedah penaburan sisa daripada unsur unit ke nod domain. Skema ini boleh mencapai tertib kejituan yang tinggi dengan stencil yang padat. Ciri ini membolehkan pengkomputeran selari yang lebih efisien serta penyelesaian yang lebih tepat dengan grid yang tidak tersusun. Kaedah klasikal dalam skema ini tidak dapat mencapai penyelesaian berjitu tinggi dalam situasi aliran dan penyebaran, serta dalam situasi transien. Analisis ralat pangakasan menunjukkan kaedah klasikal hanya mencapai tertib kejituan kedua dalam arah normal kepada garis strim, tetapi tertib pertama dalam arah selari dengan garis strim. Kaedah baru yang menggunakan hukum termodinamik kedua, iaitu penjanaan entropi dalam sistem fizikal, boleh mencapai penyelesaian yang lebih tepat, dengan tertib kejituan kedua dalam arah normal dan selari dengan garis strim. Kaedah ini juga boleh mengadun kaedah tertib kejituan rendah dan tinggi untuk memastikan kepositifan dalam penyelesaian yang mempunyai ketakselanjaran, serta penyelesaian yang tepat di bahagian licin. Walaubagaimanapun, kaedah tertib kejituan rendah tersebut terlalu meresap dan memerlukan kajian yang lebih terperinci. _______________________________________________________________________________________________________ Residual-Distribution deals with the distribution of signals to the nodes, and is true multi-dimensional. It is able to achieve higher-order accuracy with compact stencil. This compactness allows more efficient computing in parallel architecture and less sensitive to grid quality. However, the classical methods, although achieving at least second-order accuracy in the pure advection cases, drops to first-order in cases where both advection and diffusion are equally important, as well as in unsteady cases. The TE analysis shows that although the method is second-order accurate in direction normals to the streamline, but only first-order accurate along the streamline where the information is required in both advection-diffusion and unsteady cases. This research uses a new RD method incorporated with 2nd of thermodynamics —the generation of entropy in any physical systems— this was built upon the framework by Ismail and Roe in 2009. The distribution method is able to achieve second-order in space for both normals and streamline direction of the solution. This research shows that the method is able to maintain second-order accuracy for both advection-diffusion and unsteady cases. Moreover, this method allows straightforward blending of low-order and high-order solution to maintain the monotinicity at discontinuous profile, whilst having high-order solution at smooth region. However, the low-order entropy approach is very diffusive and warrants a more thorough analysis to improve its accuracy.
Contributor(s):
Sang Jit Chern - Author
Primary Item Type:
Final Year Project
Identifiers:
Accession Number : 875006738
Barcode : 00003105245
Language:
English
Subject Keywords:
Residual-Distribution; multi-dimensional; compact stencil
First presented to the public:
6/1/2016
Original Publication Date:
5/15/2018
Previously Published By:
Universiti Sains Malaysia
Place Of Publication:
School of Aerospace Engineering
Citation:
Extents:
Number of Pages - 105
License Grantor / Date Granted:
  / ( View License )
Date Deposited
2018-05-15 11:47:46.074
Date Last Updated
2020-05-05 14:39:14.694
Submitter:
Mohd Jasnizam Mohd Salleh

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Entropy-stable residual distribution methods for unsteady scalar equations1 2018-05-15 11:47:46.074