International Journal for Numerical Methods in Fluids

Cover image for Vol. 72 Issue 11

20 August 2013

Volume 72, Issue 11

Pages 1117–1218

  1. Research Articles

    1. Top of page
    2. Research Articles
    1. Numerical diffusion for flow-aligned unstructured grids with application to estuarine modeling (pages 1117–1145)

      Rusty Holleman, Oliver Fringer and Mark Stacey

      Version of Record online: 10 FEB 2013 | DOI: 10.1002/fld.3774

      Thumbnail image of graphical abstract

      Unstructured grids in hydrodynamic simulations offer great flexibility but exhibit numerical diffusion, which is dependent on orientation of the cells relative to the flow. Analytical descriptions of this relationship are found for a finite-volume scheme implementing scalar transport on regular triangular grids. An unsupervised method for generating grids locally aligned with the dominant flow is presented and shown to significantly decrease across-flow grid diffusion.

    2. On the uncertainty of CFD in sail aerodynamics (pages 1146–1164)

      I.M. Viola, P. Bot and M. Riotte

      Version of Record online: 15 FEB 2013 | DOI: 10.1002/fld.3780

      Thumbnail image of graphical abstract

      A verification and validation procedure for yacht sail aerodynamics is presented. Guidelines and an example of application are provided. The importance of verification and validation to assess modelling error and ranking different deign candidates is discussed. In the presented example, lift, drag and L2 norm of the pressures were computed with uncertainties of the order of 1% with a number of cells of the order of one million.

    3. A pressure-based method with AUSM-type fluxes for MHD flows at arbitrary Mach numbers (pages 1165–1182)

      C.M. Xisto, J.C. Páscoa and P.J. Oliveira

      Version of Record online: 14 FEB 2013 | DOI: 10.1002/fld.3781

      Thumbnail image of graphical abstract

      In the following paper, we propose a brand new method for solving the magnetohydrodynamic (MHD) equations. This is a first time presentation of the Inclusion of Advection Upstream Splitting Method-MHD fluxes for solving the ideal MHD equations with a PISO type algorithm. A detailed validation is presented using canonical test cases to prove the claimed findings.

    4. A quasi-dynamic procedure for coupled thermal simulations (pages 1183–1206)

      Marc-Paul Errera and Bénédicte Baqué

      Version of Record online: 7 MAR 2013 | DOI: 10.1002/fld.3782

      Thumbnail image of graphical abstract

      Our goal is to study the transient heat load within solid structures of complex geometries via a fluid-structure coupling. This coupling is challenging because of the great disparities in time scales of the physical models. In the quasi-dynamic procedure proposed in the paper, a solid transient state is coupled with a sequence of fluid steady states. A numerical application simulating the severe thermal conditions of a solid propellant rocket has shown that the CPU time is greatly reduced, while maintaining a very good accuracy.

    5. Improved error and work estimates for high-order elements (pages 1207–1218)

      Rainald Löhner

      Version of Record online: 17 FEB 2013 | DOI: 10.1002/fld.3783

      Thumbnail image of graphical abstract

      The comparison of error and work estimates shows that even for relative accuracy in the 0.1% range, which is one order below the typical accuracy of engineering interest (1% range), linear elements may outperform all higher-order elements. As expected, the estimates also show that the optimal order of elements in terms of work and storage demands depends on the desired relative accuracy. The comparison of work estimates for high-order elements and their finite difference counterparts reveals a work-ratio of several orders of magnitude. It thus becomes questionable if general geometric flexibility via micro-unstructured grids is worth such a high cost.