NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsDirect Numerical Simulation of Incompressible Pipe Flow Using a B-Spline Spectral MethodA numerical method based on b-spline polynomials was developed to study incompressible flows in cylindrical geometries. A b-spline method has the advantages of possessing spectral accuracy and the flexibility of standard finite element methods. Using this method it was possible to ensure regularity of the solution near the origin, i.e. smoothness and boundedness. Because b-splines have compact support, it is also possible to remove b-splines near the center to alleviate the constraint placed on the time step by an overly fine grid. Using the natural periodicity in the azimuthal direction and approximating the streamwise direction as periodic, so-called time evolving flow, greatly reduced the cost and complexity of the computations. A direct numerical simulation of pipe flow was carried out using the method described above at a Reynolds number of 5600 based on diameter and bulk velocity. General knowledge of pipe flow and the availability of experimental measurements make pipe flow the ideal test case with which to validate the numerical method. Results indicated that high flatness levels of the radial component of velocity in the near wall region are physical; regions of high radial velocity were detected and appear to be related to high speed streaks in the boundary layer. Budgets of Reynolds stress transport equations showed close similarity with those of channel flow. However contrary to channel flow, the log layer of pipe flow is not homogeneous for the present Reynolds number. A topological method based on a classification of the invariants of the velocity gradient tensor was used. Plotting iso-surfaces of the discriminant of the invariants proved to be a good method for identifying vortical eddies in the flow field.Document ID19970011270Acquisition SourceAmes Research CenterDocument TypeTechnical Memorandum (TM)AuthorsLoulou, Patrick*(Stanford Univ. Stanford, CA United States)*Moser, Robert D.*(NASA Ames Research Center Moffett Field, CA United States)*Mansour, Nagi N.*(NASA Ames Research Center Moffett Field, CA United States)*Cantwell, Brian J.*(Stanford Univ. Stanford, CA United States)*Date AcquiredSeptember 6, 2013Publication DateFebruary 1, 1997Subject CategoryFluid Mechanics And Heat TransferReport/Patent NumberA-975743NAS 1.15:110436NASA-TM-110436Accession Number97N16235Funding Number(s)PROJECT: RTOP 505-59-53Distribution LimitsPublicCopyrightWork of the US Gov. Public Use Permitted.Available DownloadsNameType19970011270.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsThere are no records associated with this record.visibility_offNo Preview Available
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