Development and Verification of Enclosure Radiation Capabilities in the CHarring Ablator Response (CHAR) code

Salazar, Giovanni; Droba, Justin; Oliver, Brandon; Amar, Adam J.

doi:10.2514/6.2016-3388

Cited by 2 publications

(3 citation statements)

References 8 publications

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“…16 Finally for the energy equation, a specified surface temperature (Dirichlet) condition is also available. For the gas mass conservation equation, specified mass flux and specified pressure (Dirichlet) conditions are available.…”

Section: Boundary Conditionsmentioning

confidence: 99%

“…Supported element types include: The semidiscrete weak form of the system given by Eqns. (16) and (17) is discretized in time using backward finitedifference schemes. Both first-and second-order accurate schemes may be derived from Taylor series expansions in time about U n+1 as outlined by Kirk 26 (18) where the weights are given for p = 1 and p = 2 in Table 1.…”

Section: Iva Finite-element Formulationmentioning

confidence: 99%

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Overview of the CHarring Ablator Response (CHAR) Code

Amar

Oliver

Kirk

et al. 2016

46th AIAA Thermophysics Conference

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JSC Engineering, Technology, and Science (JETS): Jacobs Technology and HX5, LLC An overview of the capabilities of the CHarring Ablator Response (CHAR) code is presented. CHAR is a one-, two-, and three-dimensional unstructured continuous Galerkin finite-element heat conduction and ablation solver with both direct and inverse modes. Additionally, CHAR includes a coupled linear thermoelastic solver for determination of internal stresses induced from the temperature field and surface loading. Background on the development process, governing equations, material models, discretization techniques, and numerical methods is provided. Special focus is put on the available boundary conditions including thermochemical ablation and contact interfaces, and example simulations are included. Finally, a discussion of ongoing development efforts is presented. Nomenclature α thermal diffusivity ( m 2 /sec) or coefficient of thermal expansion (K −1 ) or absorptivity α t , β t , γ t temporal finite-difference weights (sec −1 ) β extent of reaction also referred to as degree of char for volume fraction in virgin material γ P parameters for defining gas flow contact model stability ( m 2 /sec) and (sec) n unit normal vector κ permeability (m 2 ) λ Lamé's first parameter (Pa) or blowing reduction parameter R residual µ dynamic viscosity (Pa · sec) or Lamé's second parameters (Pa) ν Poisson's ratio Ω domain volume (m 3 ) φ porosity * Applied Aeroscience and CFD Branch 1 of 37 American Institute of Aeronautics and Astronautics Downloaded by MONASH UNIVERSITY on June 23, 2016 | http://arc.aiaa.org | This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. AIAA Aviation ψ basis function ρ density ( kg /m 3 ) ρ e u e C H heat transfer film coefficient ( kg /m 2 ·sec) σ Stefan-Boltzmann constant ( W /m 2 ·K 4 ) or stress (Pa) σ P gas flow contact model stability parameter ( m /sec) and ( sec /m) σ T thermal contact model stability parameter ( W /m 2 ·K) τ shear stress (Pa) α coefficient of thermal expansion tensor (K −1 ) σ shear stress tensor (Pa) ε mechanical strain tensor C rotation matrix to shift coordinate reference framẽ K stiffness tensor (Pa) κ permeability tensor (m 2 ) k thermal conductivity tensor ( W /m·K) ε emissivity A element face area (m 2 ) b Klinkenberg parameter (Pa) B non-dimensional mass flux C specific heat ( J /kg·K) C H convective heat transfer Stanton number DE discretization error E activation energy ( J /kg) or Young's modulus (Pa) e o total internal energy ( J /kg) H convective heat transfer coefficient ( Wpre-exponential factor (sec −1 ) or roughness height (m) or thermal conductivity ( W /m·K) k + non-dimensional roughness height m reaction order N number of nodes nc number of components P pressure (Pa) p temporal order of accuracy q spatial order of accuracyfunction y effective mass fractions in solid DoF acronym for degree of freedom PDE acronym for partial differential equation TC abbreviation for thermocouple TPS acronym for thermal protection...

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Section: Boundary Conditionsmentioning

confidence: 99%

Section: Iva Finite-element Formulationmentioning

confidence: 99%

Overview of the CHarring Ablator Response (CHAR) Code

Amar

Oliver

Kirk

et al. 2016

46th AIAA Thermophysics Conference

Self Cite

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“…The mesh motion algorithms described in this paper have become a permanent part of this software package. For an overview of the extensive capabilities of CHAR, see [1] and [16]. The PDE of choice for mesh motion in CHAR is linear elasticity, which has operator L…”

Section: Verificationmentioning

confidence: 99%

Tangle-free Finite Element Mesh Motion for Ablation Problems

Droba

2016

46th AIAA Thermophysics Conference

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JSC Engineering, Technology, and Science (JETS): Jacobs Technology and HX5, LLC Mesh motion is the process by which a computational domain is updated in time to reflect physical changes in the material the domain represents. Such a technique is needed in the study of the thermal response of ablative materials, which erode when strong heating is applied to the boundary. Traditionally, the thermal solver is coupled with a linear elastic or biharmonic system whose sole purpose is to update mesh node locations in response to altering boundary heating. Simple mesh motion algorithms rely on boundary surface normals. In such schemes, evolution in time will eventually cause the mesh to intersect and "tangle" with itself, causing failure. Furthermore, such schemes are greatly limited in the problems geometries on which they will be successful. This paper presents a comprehensive and sophisticated scheme that tailors the directions of motion based on context. By choosing directions for each node smartly, the inevitable tangle can be completely avoided and mesh motion on complex geometries can be modeled accurately.

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Development and Verification of Enclosure Radiation Capabilities in the CHarring Ablator Response (CHAR) code

Cited by 2 publications

References 8 publications

Overview of the CHarring Ablator Response (CHAR) Code

Overview of the CHarring Ablator Response (CHAR) Code

Tangle-free Finite Element Mesh Motion for Ablation Problems

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