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Item type:Publication, Access status: without files , Decoupling of control and force objective in adjoint-based fluid dynamic shape optimizationPublicationtype: Journal Article304 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Adjoint complement to viscous finite-volume pressure-correction methodsA hybrid-adjoint Navier-Stokes method for the pressure-based computation of hydrodynamic objective functional derivatives with respect to the shape is systematically derived in three steps: The underlying adjoint partial differential equations and boundary conditions for the frozen-turbulence Reynolds-averaged Navier-Stokes equations are considered in the first step. In step two, the adjoint discretisation is developed from the primal, unstructured finite-volume discretisation, such that adjoint-consistent approximations to the adjoint partial differential equations are obtained following a so-called hybrid-adjoint approach. A unified, discrete boundary description is outlined that supports high- and low-Reynolds number turbulent wall-boundary treatments for both the adjoint boundary condition and the boundary-based gradient formula. The third component focused in the development of the industrial adjoint CFD method is the adjoint counterpart to the primal pressure-correction algorithm. The approach is verified against the direct-differentiation method and an application to internal flow problems is presented.Publicationtype: Journal Article130 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Adjoint Navier-Stokes methods for hydrodynamic shape optimisation(2012); To efficiently calculate the sensitivity derivative of hydrodynamic objective functionals with respect to the shape, the adjoint Navier-Stokes equations were derived analytically. Consistent adjoint discretisation schemes were developed term-wise from the primal finite-volume discretisation. The adjoint method, implemented in the framework of a general-purpose pressure-correction based RANS code for unstructured grids, was validated against analytical solutions and verified by means of the direct-differentiation method. The adjoint-based sensitivity derivative was computed to guide a manual re-design of a ship hull to improve the wake field. Moreover, automatic shape-optimisation runs were carried out to reduce the power loss for ducted flows.Publicationtype: Doctoral Thesis1192 4691 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Adjoint RANS with filtered shape derivatives for hydrodynamic optimisationThe adjoint RANS method has been implemented in the framework of an unstructured general-purpose finite volume code following the derive-then-discretise strategy (continuous adjoint approach). An explicit filtering technique is applied to the shape derivatives in order to extract noise from the mesh-based representation of high-resolution. In a CAD-free optimisation strategy the method is applied to a semi-circular profile in incompressible, external flow. It was observed that the filtering is particularly relevant at high Reynolds-numbers. In the complex scenario of ship hull design, the filtered shape derivative can directly be applied to the base-line configuration in order to support both manual and automatic shape optimisation.Publicationtype: Journal Article71 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Adjoint aftship re-design for wake optimisation under the influence of active propulsion(International Center for Numerical Methods in Engineering (CIMNE), 2011); ; The paper outlines means for an efficient RANS-based hull-design optimisation process. The adjoint-based wake design method previously applied to an unpropelled ship [5] was now extended to optimise a ship hull in self-propelled conditions using a body-force propeller model. The shape optimisation aimed to improve the propeller inflow conditions quantified through an established wake objective function. The redesign was carried out manually guided by an adjoint-based sensitivity analysis that provides a continuous sensitivity map over the entire hull surface. The initial design evaluation and two re-design cycles can thereby be performed on a workstation in approximately one day. The proposed method was applied to a Panmax container vessel at model-scale Reynolds number. Encouraging improvements of the wake objective function were achieved. At the same time required propulsion power was reduced at negligible changes of the displacement.Publicationtype: Conference Paper25 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 38 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Adjoint-based hull design for wake optimisationThe hull of a generic container vessel was redesigned with the aid of RANS-based adjoint sensitivity analysis in order to improve the quality of the wake field. The redesign was carried out manually at model scale using the sensitivity derivatives of two wake objective functions introduced into the adjoint method. Both flow and adjoint solvers are based on an unstructured finite volume discretisation of incompressible flow equations. The distribution of the sensitivity derivatives with respect to design parameters yields valuable insight into the design problem from the objective point of view. The method can identify key influences and lead to an improved wake field after two design cycles.Publicationtype: Journal Article54 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Zweiter Interdisziplinärer Workshop Maritime Systeme : aktuelle Ergebnisse aus laufenden Promotionsprojekten an der TUHH(Forschungsschwerpunkt Maritime Systeme der TUHH, 2010); ; ; ; Proceedings of the Second Interdisciplinary Workshop Maritime SystemsPublicationtype: Conference Proceedings1168 611