共查询到20条相似文献,搜索用时 78 毫秒
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本文运用DES(Detached-Eddy Simulation)分离涡方法,对吹风比为0.51和1.04的平板孤立直圆孔和弯圆孔下游的换热特性和漩涡结构进行了数值研究,并简要分析了下游涡量场的结构。模拟结果显示,预测的壁面温度场的趋势与实验值吻合较好;与RANS方法相比,DES方法得到了更加丰富的流场细节和旋涡结构,同时再现了冷却孔下游具有流场的间歇性,对进一步理解和研究冷却孔下游流场内的旋涡结构提供了参考。 相似文献
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应用GAO-YONG可压缩湍流模式数值模拟RAE2822翼型绕流 总被引:3,自引:0,他引:3
应用Gao-Yong可压缩湍流模式,数值模拟RAE2822二维翼型在两种不同来流情况下的跨音速粘性绕流问题.湍流模式的对流项用ROE格式离散,扩散项用中心差分格式离散,空间离散后的控制方程用多步Runge-Kutta显式时间推进格式求解.计算结果预测了翼型表面的压力系数的分布、平均速度剖面、激波的位置、马赫数等值线等情况.同时,对翼型表面激波与边界层相互干扰以及转捩问题进行分析计算,结果表明,Gao-Yong可压缩湍流模式结合适当的数值方法能够成功地模拟翼型跨音速粘性流动.最后,基于Gao-Yong可压缩湍流模式各项异性湍流粘性的机理,初步提出一种预测转捩起始位置的方法. 相似文献
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方柱绕流是典型的钝体绕流问题,蕴含了丰富的流体力学现象,对这类流动的准确预测面临着诸多挑战.采用自主发展的大涡模拟程序,对来流Mach数M=0.3,Reynolds数ReD=22 000的绕孤立方柱流动进行了细致模拟,亚格子模型使用动力涡黏模型.对计算结果的分析表明,大涡模拟所得的平均流场及Reynolds应力分布与已有实验数据和直接数值模拟结果均吻合较好,验证了预测结果的可靠性;在此基础上对瞬态流场进行了研究,展示了计算条件下方柱绕流分离转捩及尾迹区旋涡交替脱落形成Karman涡街的全过程,为更细致的流动机理探索奠定了基础. 相似文献
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三角翼涡破裂的高精度数值模拟 总被引:1,自引:0,他引:1
采用5阶精度的加权紧致非线性格式(WCNS-E-5)数值模拟65°后掠角尖前缘三角翼的大攻角跨声速绕流流场,考察低耗散、高分辨率的WCNS-E-5格式对于三角翼涡破裂模拟的适用性,及激波旋涡干扰对涡破裂点位置的影响,重点研究三角翼大攻角旋涡破裂点的突然前移.通过求解任意坐标系下的非定常雷诺平均N-S方程,采用WCNS-E-5和SST两方程湍流模型,与试验结果和文献计算结果对比,表明既有高阶精度又能光滑捕捉激波的WCNS格式在模拟三角翼旋涡破裂方面具有一定优势,其数值结果与试验结果吻合较好,三角翼大攻角旋涡破裂点的突然前移是由于跨声速流场的激波旋涡干扰. 相似文献
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本文采用DES模拟方法,模拟了ReH=40000时处于完全发展边界层中的方体绕流。分析了中垂面上物理量和流场,讨论了DES与RANS模拟结果的差异。DES模拟结果捕捉到了方体前复杂的马蹄涡系统结构及其演化过程。马蹄涡系统由发展涡、主涡、壁角涡以及它们之间一系列反向旋转的诱导涡构成。周期变化过程中,主涡不断由发展涡脱落分离出来并与壁角涡融合;新发展涡不是在马蹄涡系统上游独自形成的,而是原发展涡分离出主涡后留下的残余部分;主涡由发展涡分离出来的断裂过程由两侧开始,向中间发展汇合,最终从发展涡分离出去。 相似文献
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圆柱绕流远场旋涡结构的数值研究 总被引:5,自引:0,他引:5
基于离散涡方法求解非定常、不稳定流场。数值模拟了高雷诺数下圆柱绕流旋涡结构的发展。从流谱图、等涡量线图和涡谱图可以清晰地看出从近场初生的卡门涡街,过渡到远场的二次涡街的过程。计算结果发现:远场离散涡有形成 二个涡的涡对及三个涡的涡对结构的趋势。计算结果说明了流体运动中涡对结构的本质:远场形成的二次涡对及卡门涡街是由于流动本身的动力不稳定而引起的,从而增加对远场尾迹流及涡对结构的理解。 相似文献
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Assessing the Performance of a Three Dimensional Hybrid Central-WENO Finite Difference Scheme with Computation of a Sonic Injector in Supersonic Cross Flow 下载免费PDF全文
Wai-Sun Don Antonio de Gregorio Jean-Piero Suarez & Gustaaf B. Jacobs 《advances in applied mathematics and mechanics.》2012,4(6):719-736
A hybridization of a high order WENO-Z finite difference scheme and a high order
central finite difference method for computation of the two-dimensional Euler
equations first presented in [B. Costa and W. S. Don, J. Comput. Appl. Math., 204(2) (2007)]
is extended to three-dimensions and for parallel computation. The Hybrid scheme
switches dynamically from a WENO-Z scheme to a central scheme at any grid location
and time instance if the flow is sufficiently smooth and vice versa if the flow is
exhibiting sharp shock-type phenomena. The smoothness of the flow is determined by
a high order multi-resolution analysis. The method is tested on a benchmark sonic
flow injection in supersonic cross flow. Increase of the order of the method reduces
the numerical dissipation of the underlying schemes, which is shown to improve the
resolution of small dynamic vortical scales. Shocks are captured sharply in an
essentially non-oscillatory manner via the high order shock-capturing WENO-Z scheme.
Computations of the injector flow with a WENO-Z scheme only and with the Hybrid
scheme are in very close agreement. Thirty percent of grid points require a
computationally expensive WENO-Z scheme for high-resolution capturing of shocks,
whereas the remainder of grid points may be solved with the computationally more
affordable central scheme. The computational cost of the Hybrid scheme can be up
to a factor of one and a half lower as compared to computations with a WENO-Z scheme
only for the sonic injector benchmark. 相似文献
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Conghai Wu Sujuan Yang & Ning Zhao 《advances in applied mathematics and mechanics.》2014,6(6):830-848
In this paper, a conservative fifth-order upwind compact scheme using centered stencil
is introduced. This scheme uses asymmetric coefficients to achieve the upwind property
since the stencil is symmetric. Theoretical analysis shows that the proposed scheme is
low-dissipative and has a relatively large stability range. To maintain the convergence
rate of the whole spatial discretization, a proper non-periodic boundary scheme is also
proposed. A detailed analysis shows that the spatial discretization implemented with the
boundary scheme proposed by Pirozzoli [J. Comput. Phys., 178 (2001), pp. 81-117] is
approximately fourth-order. Furthermore, a hybrid methodology, coupling the compact
scheme with WENO scheme, is adopted for problems with discontinuities. Numerical results
demonstrate the effectiveness of the proposed scheme. 相似文献
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LIN Xiu LI Hong-Cai YANG Rong-Can HUANG Zhi-Ping 《理论物理通讯》2008,49(3):621-624
An alternative scheme is proposed for teleportation of an unknown atomic-entangled state. The scheme is based on the resonant interaction of a two-mode cavity field with a A-type three-level atom. In contrast with the previously proposed scheme of [Commun. Theor. Phys. 47 (2007) 253], the present scheme is ascendant, since the fidelity is 1.0 in principle similarly without the Bell-state measurement. The scheme may be generalized to not only the teleportation of the cavity-mode-entangled-state but also the teleportation of the multi-atomic entangled states included in generalized GHZ states. And the scheme is experimentally feasible based on the current cavity QED technique. 相似文献
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为高精度捕捉激波等流场结构,引入一种Power限制器,对NND格式和WNND格式进行改进,分别得到二阶PNND(Power NND)格式和三阶PWNND(Power WNND)格式.该Power类型格式通过Power限制器对相邻待选模板上的一阶导数进行限制,改善了NND格式和WNND格式在间断附近的耗散效应.对各种格式的分析表明,在间断附近采用Power限制器的格式比原格式的表现要好,耗散小且捕捉间断精度高,其中PNND格式虽然只有二阶精度,但在所有算例中与三阶WNND格式的计算结果比较接近,在个别算例中甚至优于WNND格式.最后将PWNND格式应用到二维NACA0012翼型的强迫俯仰振动的数值模拟,计算结果与实验值、参考计算值吻合较好. 相似文献
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基于两原子同时和腔场共振作用制备两原子纠缠态的腔QED方案(英文) 总被引:1,自引:1,他引:0
我们提出了一个将两个远离的原子制备成纠缠态的腔QED方案,该方案基于两个原子同时和一个腔场发生共振作用.在这个方案里,我们利用一个事先制备好的纠缠态将另外两个分离的原子制备成纠缠态.该方案仅包含两个原子和腔场的共振相互作用,不需要用腔场存储量子信息,并且原子和腔场作用时间极短.因此,我们的方案基于目前的腔QED技术是可以实现的. 相似文献
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Entanglement swapping without joint measurement via a Λ-type atom interacting with bimodal cavity field 下载免费PDF全文
This paper proposes a scheme for realizing entanglement swapping in cavity QED. The scheme is based on the resonant interaction of a two-mode cavity field with a ∧-type three-level atom. In contrast with the previously proposed schemes, the present scheme is ascendant, since the fidelity is 1.0 and the joint measurement isn't needed. And the scheme is experimentally feasible based on the current cavity QED technique. 相似文献
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In this paper,a high-resolution,hybrid compact-WENO scheme is developed based on the minimized dispersion and controllable dissipation reconstruction technique.Firstly,a suffcient condition for a family of tri-diagonal compact schemes to have independent dispersion and dissipation is derived.Then,a specific 4th order compact scheme with low dispersion and adjustable dissipation is constructed and analyzed.Finally,the optimized compact scheme is blended with the WENO scheme to form the hybrid scheme.Moreover,the approximation dispersion relation approach is employed to optimize the spectral properties of the nonlinear scheme to yield the true wave propagation behavior of the finite difference scheme.Several test cases are carried out to verify the highresolution as well as the robust shock-capturing capabilities of the proposed scheme. 相似文献
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A scheme is proposed for generating three-dimensional maximally entangled states for two atoms. In the scheme the atoms are trapped in a two-mode cavity. The scheme only requires a single resonant interaction of the atoms with the cavity modes. Therefore, the scheme is very simple and required interaction time is very short, which is important in view of decoherence. 相似文献
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This research is aimed to create a new and robust family of convective schemes to capture the interface between the dispersed and the carrier phases in a spray without the need to build up the interface boundary. The selection of the Weighted Average Flux (WAF) scheme is due to this scheme being designed to deal with random flux scheme which is second-order accurate in space and time. The convective flux in each cell face utilizes the WAF scheme blended with Switching Technique for Advection and Capturing of Surfaces (STACS) scheme for high resolution flux limiters. In the next step, the high resolution scheme is blended with the WAF scheme to provide the sharpness and boundedness of the interface by using switching strategy. In this work, the Eulerian–Eulerian framework of non-reactive turbulent spray is set in terms of theoretical proposed methodology namely spray moments of drop size distribution, presented by Beck and Watkins [1]. The computational spray model avoids the need to segregate the local droplet number distribution into parcels of identical droplets. The proposed scheme is tested on capturing the spray edges in modelling hollow cone sprays without need to reconstruct two-phase interface. A test is made on simple comparison between TVD scheme and WAF scheme using the same flux limiter on convective flow hollow cone spray. Results show the WAF scheme gives a better prediction than TVD scheme. The only way to check the accuracy of the presented models is by evaluating the spray sheet thickness. 相似文献
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A novel distributed spatial media-based modulation scheme is proposed in this paper by cleverly utilizing distributed spatial modulation (DSM) and media-based modulation (MBM) principles. This proposed scheme is referred to as distributed channel modulation (DCM) for relay networks. In this scheme, decode-and-forward relaying protocol is adopted, and the channel states are exploited for transmitting extra information bits by using a number of radio frequency (RF) mirrors that are placed near each relay. To provide a fair comparison with the conventional state-of-the-art schemes, the symbol error rate (SER) performance of DSM scheme is evaluated. Besides, a low complexity detection technique known as iterative maximum ratio combining (i-MRC) is used in order to reduce the receiver complexity of the proposed scheme. Simulation results demonstrate that the proposed DCM scheme significantly outperforms DSM scheme for the same average rate. It is also shown that there is a negligible degradation in the SER performance of the proposed DCM scheme when i-MRC detection is used as compared to the performance with maximum likelihood (ML) detection. Furthermore, a significant reduction in the receiver complexity is achieved by using i-MRC detection technique in contrast to the results with ML detector. It has been also revealed that the proposed DCM scheme shows a performance drop of about 3 dB when the availability of an imperfect channel state information (CSI) is assumed with the presence of channel estimation errors (CEEs). Finally, simulation results have confirmed the analytical findings. 相似文献