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形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2018-09-30, 資料番号: PA1910002000

Accepted: 2017-10-05, 資料番号: SA1170187000

Accepted: 2016-03-24, 資料番号: SA1160148000

The newly developed unifying discontinuous formulation named the correction pro- cedure via reconstruction (CPR) for conservation laws is extended to solve the Navier-Stokes equations for 3D mixed grids. In the current development, tetrahedrons and triangular prisms are considered. The CPR method can unify several popular high order methods including the dis- continuous Galerkin and the spectral volume methods into a more efficient differential form. By selecting the solution points to coincide with the flux points, solution reconstruction can be com- pletely avoided. Accuracy studies confirmed that the optimal order of accuracy can be achieved with the method. Several benchmark test cases are computed by solving the Euler and compress- ible Navier-Stokes equations to demonstrate its performance.

An efficient implicit lower-upper symmetric Gauss-Seidel (LU-SGS) solu- tion approach has been applied to a high order spectral volume (SV) method for un- structured tetrahedral grids. The LU-SGS solver is preconditioned by the block ele- ment matrix, and the system of equations is then solved with a LU decomposition. The compact feature of SV reconstruction facilitates the efficient solution algorithm even for high order discretizations. The developed implicit solver has shown more than an order of magnitude of speed-up relative to the Runge-Kutta explicit scheme for typical inviscid and viscous problems. A convergence to a high order solution for high Reynolds number transonic flow over a 3D wing with a one equation turbulence model is also indicated. AMS subject classifications: 65M70, 76M12, 76M22

Vertical distributions of heavy metals of core sample sediments under 150 cm in abandoned mine tailings were examined. Core samples were analyzed by XRD and further examined by ICP-AES measurements after sequential extraction with 1 mol dm-3 HC1, 10% HF, and conc. HNO3. The XRD results showed that a-quartz was a main component in the core samples. Further, based on the sequential extraction results, the distributions of trace amounts of minerals, such as chlorite, sericite, rhodochrosite, pyrite and galena in core samples which were undistinguishable by XRD analysis, were estimated. Chlorite and rhodochrosite were relatively reactive and dissolved in HCl-extraction, a-quartz and sericite were dissolved in HF-extraction, and sulfides were dissolved in HNO3-extraction. Under 40 cm-zone was relatively rich in clay minerals and carbonate where sulfate-reducing bacteria were active. Under 120 cm-zone contained pyrite-rich sediments. At present the function of sulfate-reducing bacteria is not so large to affect to the mineralogy in the sediment.

The optimum condition for adding Cu-complexes was investigated to inhibit the cell growth and activity of sulfate-reducing bacteria, Desulfovibrio desulfuricans, in water-based cutting fluids. Addition of 0.1 mmol dm-3 Cu-complexes inhibited cell growth of D. desulfuricans on agar plating culture, but more than 0.2 mmol dm-3 Cu-EDTA was needed to keep inhibiting cell growth and sulfate-reducing activity of D. desulfuricans for more than one month in liquid medium. However, more than 0.5 mmol dm-3 Cu-EDTA and more than 0.2 mmol dm-3 Cu-TEA were chemically unstable, having not kept the initial Cu concentrations in water-based cutting fluids at pHs 7.5-9.25 for one month. Considering cellular inhibition and saving costs, it is optimum to use 0.2 mmol dm-3 Cu-EDTA obtained by electrolysis at weak alkaline pHs in water-based cutting fluids.

A major problem with water-based cutting fluids is bacterial propagation that can quickly ruin the fluid's effectiveness and cause rancid smell. Effects of copper triethanolamine (Cu-TEA) and copper ethylenediaminetetraacetic acid, disodium (Cu-EDTA) on the colony forming activity of sulfate-reducing bacteria (SRB) have been investigated. The copper complexes were prepared by direct addition of TEA or EDTA to the copper sulfate solution, or by electrolysis with copper electrode in complexing agent solutions. In the copper complexes, the mole ratio of copper ions to TEA or EDTA was 1：1, respectively. The growth of SRB was affected by the addition of Cu-TEA or Cu-EDTA and inhibited strongly at 0.1 mmol dm-3 copper concentration. From the data available, no obvious difference was observed between the copper complexes regarding the colony formation of SRB.

A cell-centered finite volume flow solver LS-FLOW that has been developed by JEDI/JAXA is applied to benchmark RANS simulations, and the solution accuracy and the computational efficiency are investigated. LS-FLOW can handle unstructured grids consisting of arbitrary polyhedral cells. A high-order flux reconstruction (FR) scheme on unstructured hexahedral grids has been developed and devised in LS-FLOW recently. The developed high-order unstructured grid solver is also assessed for the benchmark cases. Comparisons of the results obtained by the second order FVM and the higher-order FR method indicate that the FR solver can be competitive with the FVM in terms of the computational time by employing similar basic solution algorithms such as LU-SGS scheme for the same number of degrees of freedom, and also that the higher-order method can provide accurate result more efficiently for certain case of steady RANS simulation.

A high-order flux reconstruction (FR) scheme on unstructured hexahedral grids is coupled with the localized artificial diffusivity (LAD) scheme for aiming at accurate simulation of shock-turbulence interactions. Suitable flux reconstruction procedure is derived for ensuring the global discrete conservation. We then propose a simple and efficient filter for obtaining smooth distribution of the artificial diffusivity on unstructured hexahedral meshes, which is one of the key issues for developing robust LAD method on unstructured meshes. The proposed scheme has favorable properties of sub-cell shock capturing with the length scale of Ο(h p ⁄ ) and superior high-order-accuracy preservation for smooth flows. The proposed scheme is tested on typical shock-related problems, including 1D shock tube, 1D shock-entropy wave interaction, 2D steady shock flows, and 2D shock-vortex interaction. The comparisons between the proposed scheme, a conventional finite volume method and the FR scheme with a limiter illustrate the superior performance of the proposed FR-LAD scheme for the simulation of flows involving shocks, acoustic waves, turbulence, and their interaction.

A high-order flux reconstruction (FR) scheme on unstructured hexahedral grids is developed for aerospace flow simulation. In order to use computational grids generated by the body-fitted Cartesian (BFC) method, the grid which contains polyhedral cells with hanging nodes are subdivide into hexahedral cells first. Then, to perform computation by the FR scheme on the non-conformal hexahedral grid, the mortal element method (MEM) is employed to determine the numerical flux at cell interface. As a shock capturing scheme, the localized artificial diffusivity (LAD) method is developed for the FR scheme. The developed scheme is tested for typical benchmark problems including smooth and shocked flows. I. Introduction HE use of CFD in designing aerospace vehicles has been growing over the past decades. Commercial CFD software can be effectively used for early stage of the design process with the reasonable accuracy in quick turn around time. The finite volume methods (FVM) are widely used for the commercial and industrial CFD solvers, but the spatial order of accuracy is remained less than 2 nd -order due to several reasons mainly related to the robustness. In order to tackle more complicated flowfields and to improve the prediction accuracy by CFD, employing highorder methods is one of the prospective directions. It is well known that high-order methods can give the numerical solution more efficiently than the low-order methods with the same level of accuracy if the flowfield is sufficiently smooth. High-order methods were developed and investigated first in the context of the structured or multi-block structured grids. The formal order of accuracy can be retained with the relatively better quality mesh in contrast to the case with unstructured grids. A main drawback with structured grids is the difficulty in the mesh generation around complex geometries. Therefore, unstructured methods are often used in the production codes. Automated processes in the unstructured grid generation has facilitated the routinely works in the design cycle and has gained more users in the wide engineering areas. A criticism for this approach is related to the solution accuracy especially on the dirty grid around real complicated configurations. Recent research for the reconstruction of the solution gradient

Acoustic test using Mach 2 cold jet was conducted for the H3 launch vehicle currently being developed in Japan. Effect of the clustered engines and the newly built movable launcher on the lift-off acoustics was investigated. The overall acoustic level taken by the farfield microphones did not show proportional increase in the number of engines, especially for the angles corresponding to the Mach wave radiation from the free jets. The observation here disagrees with the empirical prediction model. The computational fluid dynamics was also employed to analyze the acoustic mechanism of clustered engines.

Recently a differential discontinuous formulation for conservation laws named the Correction Procedure via Reconstruction (CPR) was developed. CPR is inspired by several other discontinuous methods such as the discontinuous Galerkin, spectral volume and spectral difference methods. In fact, all of them can be unified under the CPR framework, which is relatively simple to implement. The aim of the present work is to investigate and develop an efficient solution algorithm for high speed viscous flows using the high-order CPR discretization. A p-multigrid solver and an implicit line solver are developed and tested on several test cases to show the performance.

A unifying discontinuous formulation named the correction procedure via reconstruction (CPR) for conservation laws is extended to solve the Navier–Stokes equations for mixed grids. The CPR framework can unify several popular high order methods including the discontinuous Galerkin and the spectral volume methods into a differential formulation without explicit volume or surface integrations. Several test cases are computed to demonstrate its performance.

The newly developed unifying discontinuous formulation based on flux reconstruction and lifting collocation penalty (LCP) approaches for conservation laws is extended to solve the Navier-Stokes equations for 3D mixed grids. In the current development, tetrahedrons and triangular prisms are considered. The LCP formulation is an extension of the flux reconstruction (FR) method to arbitrary element types. As with the FR method, it can unify several popular high order methods including the discontinuous Galerkin and the spectral volume methods into a more efficient differential form without any explicit integration. By selecting the solution points to coincide the flux points, solution reconstruction can be completely avoided. Numerical accuracy of the scheme is assessed for grid refinement studies. Several typical test cases are computed by solving the Euler equations and the compressible Navier-Stokes equations to demonstrate its performance.

An aerodynamic s simulation code for the Reynolds averaged Navier -Stokes (RANS) equations is developed using the spectral volu me method for unstructured tetrahedral meshes . The turbulent viscousity is modeled by the Spalart -Allmaras (SA) one -equation model. Distributions of the state variables and their gradients in each grid cell are reconstructed using piece -wise linear polynomials with a modified SV limiter near shocks and steep gradients. For time integration, the non -linear LU -SGS scheme is employed to r educe total CPU times. The developed scheme is validated for turbulent flow over a flat plate and assessed for transonic flowfield over a wing compared with availab le CFD results . Then, RANS simulation around the JAXA high -lift configuration model is perfo rmed using developed scheme. By comparing with the numerical solutions obtained by the conventional finite volume solver, we examine the accuracy and the computational cost of the present SV method. Comparisons with the available experimental data are also attempted.

An appropriate procedure to construct the symmetric conservative metrics is presented in the high-order conservative flux-reconstruction scheme. The present framework enables a direct discretization of the strong conservation form of governing equations without any errors in the freestream preservation and global conservation properties on threedimensionally moving and deforming grids. We show that a straightforward implementation of the symmetric conservative metrics often fails to construct metric polynomials with the same order of a solution polynomial, which severely degrades a numerical accuracy. On the other hand, the symmetric conservative metrics constructed by the appropriate procedure can preserve the freestream solution regardless of the order of shape functions; in addition, a convecting vortex is more accurately computed on deforming grids. The global conservation property is also demonstrated numerically for the convecting vortex on deforming grids.

The vertical distributions of heavy metals and other elements in sediment core samples in a landfill of abandoned mine tailings were examined. Core samples were analyzed by XRF and XRD, and further examined by ICP-AES measurements after acid-sequential extraction with HCl, HF, and HNO3. According to XRD, the sediments contained α-quartz as the main component, and sericite, chlorite, rhodochrosite, pyrite, jarosite, sphalerite, and galena as minor components. A complete decomposition method using sequential extraction for the mine tailings sediments was established at ambient temperatures. Acid sequential extraction was useful for the analysis of minerals in mine tailings which are difficult to detect by XRD. Rhodochrosite and chlorite were dissolved by HCl-extraction, quartz and sericite by HF-extraction, and sulfides by HNO3-extraction. Rhodochrosite was the main source of high concentrations of Mn in mine drainage, highly distributed below the −100 cm zone in the mine tailings, combined with pyrite but not with sericite and quartz. The distributions of most heavy metals were related to those of pyrite.