874 research outputs found
A conservative coupling algorithm between a compressible flow and a rigid body using an Embedded Boundary method
This paper deals with a new solid-fluid coupling algorithm between a rigid
body and an unsteady compressible fluid flow, using an Embedded Boundary
method. The coupling with a rigid body is a first step towards the coupling
with a Discrete Element method. The flow is computed using a Finite Volume
approach on a Cartesian grid. The expression of numerical fluxes does not
affect the general coupling algorithm and we use a one-step high-order scheme
proposed by Daru and Tenaud [Daru V,Tenaud C., J. Comput. Phys. 2004]. The
Embedded Boundary method is used to integrate the presence of a solid boundary
in the fluid. The coupling algorithm is totally explicit and ensures exact mass
conservation and a balance of momentum and energy between the fluid and the
solid. It is shown that the scheme preserves uniform movement of both fluid and
solid and introduces no numerical boundary roughness. The effciency of the
method is demonstrated on challenging one- and two-dimensional benchmarks
An immersogeometric formulation for free-surface flows with application to marine engineering problems
An immersogeometric formulation is proposed to simulate free-surface flows around structures with complex geometry. The fluidâfluid interface (airâwater interface) is handled by the level set method, while the fluidâstructure interface is handled through an immersogeometric approach by immersing structures into non-boundary-fitted meshes and enforcing Dirichlet boundary conditions weakly. Residual-based variational multiscale method (RBVMS) is employed to stabilize the coupled NavierâStokes equations of incompressible flows and level set convection equation. Other level set techniques, including re-distancing and mass balancing, are also incorporated into the immersed formulation. Adaptive quadrature rule is used to better capture the geometry of the immersed structure boundary by accurately integrating the intersected background elements. Generalized-α role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 16.2px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative; \u3eα method is adopted for time integration, which results in a two-stage predictor multi-corrector algorithm. GMRES solver preconditioned with block Jacobian matrices of individual fluid and level set subproblems is used for solving the coupled linear systems arising from the multi-corrector stage. The capability and accuracy of the proposed method are assessed by simulating three challenging marine engineering problems, which are a solitary wave impacting a stationary platform, dam break with an obstacle, and planing of a DTMB 5415 ship model. A refinement study is performed. The predictions of key quantities of interest by the proposed formulation are in good agreement with experimental results and boundary-fitted simulation results from others. The proposed formulation has great potential for wide applications in marine engineering problems
Efficient aeroelastic analysis of inflatable structures using enhanced potential flow aerodynamics
An efficient method for the aeroelastic analysis of wind effects on inflatable structures is presented. The solution scheme is staggered and uses an explicit finite-element structural solver and potential flow aerodynamics. In order to take into account the essential features of the flow around blunt-shaped structures, a physics-based correction of the inviscid solution is proposed. The procedure involves automatic prediction of the detached flow areas (using Stratfordâs criterion) and an empirical modification of the calculated pressure field intended to match the real viscous behavior. Several validation benchmarks and a realistic application example are presented. The results show the capability of the model to predict the wind loads on the structure with sufficient accuracy and low computational cost, making it possible to use aeroelastic analysis for routine calculation of inflatable structures.Peer ReviewedPostprint (author's final draft
Spectral/hp element methods: recent developments, applications, and perspectives
The spectral/hp element method combines the geometric flexibility of the
classical h-type finite element technique with the desirable numerical
properties of spectral methods, employing high-degree piecewise polynomial
basis functions on coarse finite element-type meshes. The spatial approximation
is based upon orthogonal polynomials, such as Legendre or Chebychev
polynomials, modified to accommodate C0-continuous expansions. Computationally
and theoretically, by increasing the polynomial order p, high-precision
solutions and fast convergence can be obtained and, in particular, under
certain regularity assumptions an exponential reduction in approximation error
between numerical and exact solutions can be achieved. This method has now been
applied in many simulation studies of both fundamental and practical
engineering flows. This paper briefly describes the formulation of the
spectral/hp element method and provides an overview of its application to
computational fluid dynamics. In particular, it focuses on the use the
spectral/hp element method in transitional flows and ocean engineering.
Finally, some of the major challenges to be overcome in order to use the
spectral/hp element method in more complex science and engineering applications
are discussed
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