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The mean momentum and heavy mass fraction, turbulent kinetic energy, and heavy mass fraction variance fields, as well as the budgets of their transport equations, are examined at several times during the evolution of a narrowband Richtmyer-Meshkov instability initiated by a Mach 1.84 shock traversing a perturbed interface separating gases with a density ratio of 3. The results are computed using the `quarter scale' data from four algorithms presented in the \theta-group study of Thornber et al. [Phys. Fluids 29, 105107 (2017)]. The present study is inspired by a previous similar study of Rayleigh-Taylor instability and mixing using direct numerical simulation data by Schilling and Mueschke [Phys. Fluids 22, 105102 (2010)]. In addition to comparing the predictions of the data from four implicit large-eddy simulation codes, the budgets are used to quantify the relative importance of the terms in the transport equations, and the balance of the terms is employed to infer the numerical dissipation. Terms arising from the compressibility of the flow are examined in particular, i.e., the pressure-dilatation. The results are useful for validation of large-eddy simulation and Reynolds-averaged modeling of Richtmyer-Meshkov instability., Comment: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Physics of Fluids 31, 096105 (2019) and may be found at https://aip.scitation.org/doi/abs/10.1063/1.5111681

Turbulent Richtmyer--Meshkov instability (RMI) is investigated through a series of high resolution three dimensional smulations of two initial conditions with eight independent codes. The simulations are initialised with a narrowband perturbation such that instability growth is due to non-linear coupling/backscatter from the energetic modes, thus generating the lowest expected growth rate from a pure RMI. By independently assessing the results from each algorithm, and computing ensemble averages of multiple algorithms, the results allow a quantification of key flow properties as well as the uncertainty due to differing numerical approaches. A new analytical model predicting the initial layer growth for a multimode narrowband perturbation is presented, along with two models for the linear and non-linear regime combined. Overall, the growth rate exponent is determined as $\theta=0.292 \pm 0.009$, in good agreement with prior studies; however, the exponent is decaying slowly in time. $\theta$ is shown to be relatively insensitive to the choice of mixing layer width measurement. The asymptotic integral molecular mixing measures $\Theta=0.792\pm 0.014$, $\Xi=0.800 \pm 0.014$ and $\Psi=0.782\pm 0.013$ which are lower than some experimental measurements but within the range of prior numerical studies. The flow field is shown to be persistently anisotropic for all algorithms, at the latest time having between 49\% and 66\% higher kinetic energy in the shock parallel direction compared to perpendicular and does not show any return to isotropy. The plane averaged volume fraction profiles at different time instants collapse reasonably well when scaled by the integral width, implying that the layer can be described by a single length scale and thus a single $\theta$. Quantitative data given for both ensemble averages and individual algorithms provide useful benchmark results for future research., Comment: 50 pages

We measured isofield magnetization curves as a function of temperature in two single crystal of deoxygenated YBaCuO with T_c = 52 and 41.5 K. Isofield MvsT were obtained for fields running from 0.05 to 4 kOe. The reversible region of the magnetization curves was analyzed in terms of a scaling proposed by Prange, but searching for the best exponent $\upsilon$. The scaling analysis carried out for each data sample set with $\upsilon$=0.669, which corresponds to the 3D-xy exponent, did not produced a collapsing of curves when applied to MvsT curves data obtained for the lowest fields. The resulting analysis for the Y123 crystal with T_c = 41.5 K, shows that lower field curves collapse over the entire reversible region following the Prange's scaling with $\upsilon$=1, suggesting a two-dimensional behavior. It is shown that the same data obeying the Prange's scaling with $\upsilon$=1 for crystal with T_c = 41.5 K, as well low field data for crystal with $T_c$ = 52 K, obey the known two-dimensional scaling law obtained in the lowest-Landau-level approximation., Comment: 4 pages, 3 figures

This letter describes a very simple electromechanical oscillator, consisting of a strong-pinning Nb-Ti superconductor loop subjected to static magnetic fields. A detailed calculation of the losses occurring during its low-frequency oscillations is carried out. The conclusion is that the quality factor for such oscillator might reach the 10^10-10^11 range, something comparable only to the best optical microcavities. Such device might permit the measurement of variations in static forces with the same precision a superconducting quantum interference device (SQUID) measures variations of magnetic field, providing a new tool for probing minute variations of the gravitational field. for instance., Comment: submitted to Applied Physics Letters

We measured magnetization, M, of a twin-aligned single crystal of YBa2Cu 3Ox (YBaCuO), with Tc = 91 K, as a function of temperature, T, and magnetic field, H, with H applied along the ab planes. Isothermal M-vs.-H and M-vs.-time curves were obtained with H applied parallel and perpendicular to the twin boundary, TB, direction. M-vs.-H curves exhibited two minimums below 38 K, which resembled similar curves that have been obtained in YBaCuO for H parallel to c axis. Above 12 K, the field positions of the minimums for H||TB and HperpTB were quite similar. Below 12 K, the position of the second minimum, Hmin, occurred at a higher field value with H||TB. Below 6 K, only one minimum appeared for both field directions. At low temperatures, these minimums in the M-vs.-H curves produced maximums in the critical current. It was determined that vortex lines were expelled more easily for H||TB than for HperpTB, and, therefore, below a certain field value, that Jc(HperpTB) was larger than Jc(H||TB) . At T<12 K with H||TB, the relaxation rate for flux lines leaving the crystal was found to be different from that for flux entering the crystal. We also observed flux jumps at low temperatures, with their sizes depending on the orientation of magnetic field with respect to the TBs., Comment: 7 pages, 6 figures. to appear in PRB Dec. 2004

We have performed a magnetic study of a bulk metallic sample of Nb with critical temperature $T_{c}=8.5$ K. Magnetization versus temperature (M {\it vs} T) data obtained for fixed magnetic fields above 1 kOe show a superconducting transition which becomes broader as the field is increased. The data are interpreted in terms of the diamagnetic lowest Landau level (LLL) fluctuation theory. The scaling analysis gives values of the superconducting transition temperature $T_{c}(H)$ consistent with $H_{c2}(T)$% . We search for universal 3D LLL behavior by comparing scaling results for Nb and YBaCuO, but obtain no evidence for universality., Comment: 5 pages, 6 figures, Accepted for publication in Phys.Rev. B