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Simulation of Axisymmetric Scramjet Combustion Flowfields Using Weno Navier-Stokes Solvers
Jaw-Yen Yang,J.C. Huang,Y S. Lai,C. S. Kuo 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.10
This study is based on the theory of gas dynamics and uses the Navier-Stokes equations as the governing equations to solve the fluid flow field problems of the scramjet. For the turbulent flow, we use the simple Spalart-Allmaras one equation turbulence model (S-A model) which produces better results for near wall and boundary layer flow field problems. The lower-upper symmetric Gauss-Seidel (LU-SGS) implicit scheme, whose results converge efficiently under steady state conditions, is combined with the Weighted Essentially Non-Oscillatory (WENO) scheme to construct a numerical model of the scramjet. Using the WENO scheme’s high-order accuracy and its non-oscillatory solution at discontinuous areas, we can solve supersonic flow field problems with multiple shock wave interactions. This simulation procedure is verified against two partial examples from literature to ensure its accuracy, and is then applied to a complete geometric model of a scramjet with different initial conditions for a full flow field analysis. The Mach number, density, static temperature and pressure are found and the results discussed. It is found that even when the shock waves are very close to each other, the WENO scheme produces better simulation results than other numerical approaches.
C.T. Hsieh,M.W. Lin,C.L. Chang,Y.C. Ho,S.Y. Chen,J. Wang,M.C. Chou,J.Y. Lin,C.H. Pai,P.H. Lin,L.C. Tai,S.H. Chen,G.Y. Tsaur,C.C. Kuo,T.Y. Chien 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6
A general method for fabricating transient plasma structures with high-intensity laser pulses is developed to gain fine control over laser-plasma interactions. These structures have been used as programmable photonic devices in the development of laser-wakefield accelerators, soft X-ray lasers and plasma nonlinear optics driven by multi-terawatt laser pulses. Plasma ramps are used to control electron injection in laser-wakefield accelerators, plasma waveguides are used to enhance the efficiency of soft X-ray lasers by orders of magnitude and periodic plasma structures are used to achieve quasi-phase matching in relativistic harmonic generation. By scanning the interaction length with the same plasma-fabrication method, tomographic measurements are carried out to resolve the injection/acceleration process in laser-wakefield accelerators and amplification processes in X-ray lasers and relativistic harmonic generation. A theoretical analysis and a computer simulation are also carried out to provide insightful pictures of these processes. These research works show that by controlling plasma structures with optical fabrication methods, laser-plasma interaction can be engineered to expand and enrich the frontier of high-field physics.
Kuo, C.T.,Balamurugan, K.,Shiu, H.W.,Park, H.J.,Sinn, S.,Neumann, M.,Han, M.,Chang, Y.J.,Chen, C.H.,Kim, H.D.,Park, J.G.,Noh, T.W. Elsevier 2016 Current Applied Physics Vol.16 No.3
<P>We have studied the electronic structure and interfacial properties of mechanically exfoliated few-layer NiPS3 van der Waals crystals on ZnO/Nb:SrTiO3 substrates using scanning photoelectron microscopy and spectroscopy. The conducting ZnO layer enhances the visibility of few-layer NiPS3 on Nb:SrTiO3 and prevents charging effects in photoemission. We experimentally determined a type-II band alignment at the NiPS3/ZnO interface. The valence band offset (VBO) of few-layer NiPS3/ZnO is 2.8 +/- 0.09 eV, and the conduction band offset is 1.0 +/- 0.09 eV. Moreover, we found an increase of similar to 0.3 eV in VBO as decreasing NiPS3 thickness, suggesting electronic coupling or charge transfer at the NiPS3/ZnO interface. (C) 2016 Elsevier B.V. All rights reserved.</P>
Ionic Size Effect on the Spin Gap Nature of SrCu2(TeO3)2Cl2
C. N. Kuo,S. C. Chen,C. S. Lue 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
By means of magnetic susceptibility measurements, we report the effects of partial substitutionof Br onto the Cl sites of SrCu2(TeO3)2Cl2. This material has been a subject of current interestdue to indications of a spin gap behavior. However, the magnetic spin couplings responsiblefor the spin gap nature remain unclear. For each composition of SrCu2(TeO3)2(Cl1−xBrx)2, thetemperature-dependent susceptibility exhibits a character of low-dimensional magnetism with abroad maximum at Tmax. The magnitude of Tmax slightly shifts to higher temperatures with increasingBr concentration. The experimental data can be well fitted to a coupled spin dimer model,yielding an increasing trend for the spin gap size from 172 to 188 K. This indicates that the substitutionof Br ions has the effect of reducing the distance between Cu(1) and Cu(2) ions, leading toa stronger antiferromagnetic spin interaction. On the other hand, the variation of the interdimercoupling is marginal, indicative of substituting Br ions having little effect on the distance changesof Cu(1)-Cu(1) and Cu(2)-Cu(2) in SrCu2(TeO3)2Cl2.