Three-Dimensional Surface Evolution and Mesh Deformation for Aircraft Icing Applications
01 May 2017-Journal of Aircraft (American Institute of Aeronautics and Astronautics)-Vol. 54, Iss: 3, pp 1047-1063
TL;DR: In this paper, a mesh generation strategy that facilitates the numerical simulation of ice accretion on realistic aircraft configurations by automating the deformation of surface and volume meshes in response to the evolving ice shape is presented.
Abstract: This paper presents a mesh generation strategy that facilitates the numerical simulation of ice accretion on realistic aircraft configurations by automating the deformation of surface and volume meshes in response to the evolving ice shape. The discrete surface evolution algorithm is based on a face-offsetting strategy that uses an eigenvalue decomposition to determine 1) the nodal offset direction and 2) a null space in which the quality of the surface mesh is improved via point redistribution. A fast algebraic technique is then used to propagate the computed surface deformations into the surrounding volume mesh. Due to inherent limitations in the icing model employed here, there is no intent to present a tool to predict three-dimensional ice accretions but, instead, to demonstrate a meshing strategy for surface evolution and mesh deformation that is appropriate for aircraft icing applications. In this context, sample results are presented for a complex glaze-ice accretion on a rectangular-planform wing ...
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TL;DR: In this paper, a radial basis function mesh deformation technique is used to update the moving ice boundary resulting from aircraft icing simulations using radial basis functions deformation techniques, and the convergence history of the multi-level greedy point selection is assessed in terms of number of control points and computational cost.
20 citations
TL;DR: In this paper , a level-set-based approach is proposed to model evolving boundary problems for in-flight ice accretion, where simple geometrical quantities are employed to provide an implicit discretization of the updated boundary.
Abstract: This paper presents a novel level-set-based approach to model evolving boundary problems for in-flight ice accretion. No partial differential equations are solved as in the standard level-set formulation, but simple geometrical quantities are employed to provide an implicit discretization of the updated boundary. This method avoids mesh entanglements and grid intersections typical of algebraic and mesh deforming techniques, making it suitable for generating a body-fitted discretization of arbitrarily complex geometries as in-flight ice shapes, including the collision of separate ice fronts. Moreover, this paper presents a local ice thickness correction, which accounts for the body’s curvature, to conserve the prescribed iced mass locally. The verification includes ice accretion over an ellipse and a manufactured example to show the proposed strategy’s advantages and robustness compared to standard algebraic methods. Finally, the method is applied to ice accretion problems. A temporal and grid convergence study is presented for automatic multistep in-flight simulations over a NACA0012 airfoil in rime, glaze, and mixed ice conditions.
7 citations
TL;DR: In this article, a quantitative assessment of flight risk under icing conditions was taken as the research object, where the flight characteristics were studied comprehensively and heavy-tail characteristics and the distributions of different flight parameters were verified.
Abstract: The quantitative assessment of flight risk under icing conditions was taken as the research object. Based on multifactor coupling modeling idea, the pilot-aircraft-environment coupling system was built. Considering the physical characteristics and randomness of aircraft icing, the extreme values of critical flight risk parameters were extracted by the Monte Carlo flight simulation experiment. The flight characteristics were studied comprehensively and heavy-tail characteristics and the distributions of different flight parameters were verified. Flight risk criterion was developed and one-dimensional extreme flight risk probability was calculated. Further, in order to solve the limitation of one-dimensional extreme value, with the Copula theory, the joint distribution model of flight parameters with three distinct distribution types was built. The optimal Copula model was selected by identification of unknown parameters and goodness of fit tests, and the three-dimensional extreme flight risk probability was defined. Based on the quantitative flight risk, the accident induction mechanism under icing conditions was discussed. Airspeed and roll angle under asymmetry icing conditions were more sensitive and had a more significant impact on flight safety. This method can provide reference for safety manipulation, boundary protection, and risk warning during icing flight.
4 citations
TL;DR: In this article , an immersed boundary method combined with a level set has been proposed to estimate 2D rime and glaze cases from the 1st AIAA Ice Prediction Workshop, showing good correspondence with the body-fitted approach.
Abstract: The numerical prediction of in-flight ice accretion involves a sequential call to different modules including mesh generation, aerodynamics, droplet trajectories, wall heat transfer, ice accretion, and geometry update. Automation of this process is critical as these solvers are embedded in a time loop that is repeated several times to obtain an accurate ice shape prediction. The robustness of ice accretion tools is often limited by the difficulty of generating meshes on complex ice shapes and also by the geometry update that can exhibit overlaps in concave regions if not treated properly. An immersed boundary method combined with a level set has the potential to alleviate these issues. The objective of this paper is twofold: confirm the potential of this methodology and assess its accuracy against the usual body-fitted approach. The proposed methodology is tested on two-dimensional (2D) rime and glaze ice cases from the 1st AIAA Ice Prediction Workshop, showing good correspondence with the body-fitted approach. The new methodology also performs well for a 2D three-element airfoil configuration when a proper mesh refinement is used. The immersed boundary method combined with the level-set ice accretion provides a viable alternative to the body-fitted approach.
4 citations
15 Jun 2020
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References
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TL;DR: In this paper, two new two-equation eddy-viscosity turbulence models are presented, which combine different elements of existing models that are considered superior to their alternatives.
Abstract: Two new two-equation eddy-viscosity turbulence models will be presented. They combine different elements of existing models that are considered superior to their alternatives. The first model, referred to as the baseline (BSL) model, utilizes the original k-ω model of Wilcox in the inner region of the boundary layer and switches to the standard k-e model in the outer region and in free shear flows. It has a performance similar to the Wilcox model, but avoids that model's strong freestream sensitivity
15,459 citations
TL;DR: In this paper, the concept of a fractional volume of fluid (VOF) has been used to approximate free boundaries in finite-difference numerical simulations, which is shown to be more flexible and efficient than other methods for treating complicated free boundary configurations.
11,567 citations
TL;DR: A level set method for capturing the interface between two fluids is combined with a variable density projection method to allow for computation of two-phase flow where the interface can merge/break and the flow can have a high Reynolds number.
4,148 citations
01 Jun 1995
TL;DR: In this article, a level set method for capturing the interface between two fluids is combined with a variable density projection method to allow for computation of two-phase flow where the interface can merge/break and the flow can have a high Reynolds number.
Abstract: A level set method for capturing the interface between two fluids is combined with a variable density projection method to allow for computation of two-phase flow where the interface can merge/break and the flow can have a high Reynolds number. A distance function formulation of the level set method enables one to compute flows with large density ratios (1000/1) and flows that are surface tension driven; with no emotional involvement. Recent work has improved the accuracy of the distance function formulation and the accuracy of the advection scheme. We compute flows involving air bubbles and water drops, to name a few. We validate our code against experiments and theory.
3,556 citations
TL;DR: The term immersed boundary (IB) method is used to encompass all such methods that simulate viscous flows with immersed (or embedded) boundaries on grids that do not conform to the shape of these boundaries.
Abstract: The term “immersed boundary method” was first used in reference to a method developed by Peskin (1972) to simulate cardiac mechanics and associated blood flow. The distinguishing feature of this method was that the entire simulation was carried out on a Cartesian grid, which did not conform to the geometry of the heart, and a novel procedure was formulated for imposing the effect of the immersed boundary (IB) on the flow. Since Peskin introduced this method, numerous modifications and refinements have been proposed and a number of variants of this approach now exist. In addition, there is another class of methods, usually referred to as “Cartesian grid methods,” which were originally developed for simulating inviscid flows with complex embedded solid boundaries on Cartesian grids (Berger & Aftosmis 1998, Clarke et al. 1986, Zeeuw & Powell 1991). These methods have been extended to simulate unsteady viscous flows (Udaykumar et al. 1996, Ye et al. 1999) and thus have capabilities similar to those of IB methods. In this review, we use the term immersed boundary (IB) method to encompass all such methods that simulate viscous flows with immersed (or embedded) boundaries on grids that do not conform to the shape of these boundaries. Furthermore, this review focuses mainly on IB methods for flows with immersed solid boundaries. Application of these and related methods to problems with liquid-liquid and liquid-gas boundaries was covered in previous reviews by Anderson et al. (1998) and Scardovelli & Zaleski (1999). Consider the simulation of flow past a solid body shown in Figure 1a. The conventional approach to this would employ structured or unstructured grids that conform to the body. Generating these grids proceeds in two sequential steps. First, a surface grid covering the boundaries b is generated. This is then used as a boundary condition to generate a grid in the volume f occupied by the fluid. If a finite-difference method is employed on a structured grid, then the differential form of the governing equations is transformed to a curvilinear coordinate system aligned with the grid lines (Ferziger & Peric 1996). Because the grid conforms to the surface of the body, the transformed equations can then be discretized in the
3,184 citations