Rotation Interaction Research Articles

Heat/mass transfer of a rotated dual wavy shape in a nanofluid-filled cavity partially saturated by porous media

This study is working on numerical simulations of thermosolutal convection of a circular rotation of a dual wavy shape in a cavity filled with a nanofluid and with two porous layers on the vertical sides. The rotated objects are applied in engineering designs including the shaft of a turbine, the trembling of a thermal fin, and the collector of solar energy. The ISPH method is proposed to solve the dimensionless form of the regulating equations. The ISPH method showed good efficiency in simulating the fluid-structure interaction of a circular rotation of a rigid dual-wavy shape within a nanofluid flow. The numerical simulations exhibited the implication of a rotational motion of an inner wavy shape in improving the transmission of heat and mass as well as the nanofluid movements. The involved physical parameters are including a dimensionless time , thermal radiation parameter , nanoparticle parameter , Rayleigh number , Hartmann number , Darcy parameter , and length of dual wavy curves . The nanofluid speed shrinks by an increase in Hartmann number, length of a dual wavy shape, and nanoparticle parameter. Besides, the nanofluid speed reduces in the vertical porous layers at a lower Darcy parameter. The thermosolutal convection is dramatically enhanced according to an augmentation of a length of a dual wavy shape, and Rayleigh number. The value of enhances by , , , and according to an increase in from 0 to 10, from 0.1–0.7, from 0 to 0.1, and from to , respectively.

Vibrationally excited states of 1H- and 2H-1,2,3-triazole isotopologues analyzed by millimeter-wave and high-resolution infrared spectroscopy with approximate state-specific quartic distortion constants.

In this work, we present the spectral analysis of 1H- and 2H-1,2,3-triazole vibrationally excited states alongside provisional and practical computational predictions of the excited-state quartic centrifugal distortion constants. The low-energy fundamental vibrational states of 1H-1,2,3-triazole and five of its deuteriated isotopologues ([1-2H]-, [4-2H]-, [5-2H]-, [4,5-2H]-, and [1,4,5-2H]-1H-1,2,3-triazole), as well as those of 2H-1,2,3-triazole and five of its deuteriated isotopologues ([2-2H]-, [4-2H]-, [2,4-2H]-, [4,5-2H]-, and [2,4,5-2H]-2H-1,2,3-triazole), are studied using millimeter-wave spectroscopy in the 130-375GHz frequency region. The normal and [2-2H]-isotopologues of 2H-1,2,3-triazole are also analyzed using high-resolution infrared spectroscopy, determining the precise energies of three of their low-energy fundamental states. The resulting spectroscopic constants for each of the vibrationally excited states are reported for the first time. Coupled-cluster vibration-rotation interaction constants are compared with each of their experimentally determined values, often showing agreement within 500kHz. Newly available coupled-cluster predictions of the excited-state quartic centrifugal distortion constants based on fourth-order vibrational perturbation theory are benchmarked using a large number of the 1,2,3-triazole tautomer isotopologues and vibrationally excited states studied.

Transition from anti-solar to solar-like differential rotation: Dependence on Prandtl number

Context. Late-type stars such as the Sun rotate differentially due to the interaction of turbulent convection and rotation. Aims. The aim of the study is to investigate the effects of the effective thermal Prandtl number, which is the ratio of kinematic viscosity to thermal diffusivity, on the transition from anti-solar (slow equator, fast poles) to solar-like (fast equator, slow poles) differential rotation. Methods. Three-dimensional hydrodynamic and magnetohydrodynamic simulations in semi-global spherical wedge geometry were used to model the convection zones of solar-like stars. Results. The overall convective velocity amplitude increases as the Prandtl number decreases, in accordance with earlier studies. The transition from anti-solar to solar-like differential rotation is insensitive to the Prandtl number for Prandtl numbers below unity, but for Prandtl numbers greater than unity, solar-like differential rotation becomes significantly harder to excite. Magnetic fields and more turbulent regimes with higher fluid and magnetic Reynolds numbers help to achieve solar-like differential rotation in near-transition cases where anti-solar rotation is found in more laminar simulations. Solar-like differential rotation occurs only in cases with radially outward turbulent angular momentum transport due to the Reynolds stress at the equator. The dominant contribution to this outward transport near the equator is due to prograde propagating thermal Rossby waves. Conclusions. The differential rotation is sensitive to the Prandtl number only for large Prandtl numbers in the parameter regime explored in this study. Magnetic fields have a greater effect on the differential rotation, although the inferred presence of a small-scale dynamo did not lead to drastically different results. The dominance of the thermal Rossby waves in the simulations is puzzling because they are not detected in the Sun. The current simulations are shown to be incompatible with the currently prevailing mean-field theory of differential rotation.

Systematic investigation and correction of the magnetic hysteresis obtained by vibrating sample magnetometry

This work focused on a systematic study of data corrections for the vibrating sample magnetometry (VSM) to obtain reliable magnetic properties of strong ferromagnets. We designed the systematic experiments by varying the length-to-radius ratio of VSM samples between 1-5 and provided the step-by-step corrections of two commercial NdFeB powder magnets with reported energy product ((BH)max ) of 6.0±0.5 and 12.7±0.5 MGOe. Without data corrections, the measured hysteresis loops yield the (BH)max between 47.3% and 62.6% of their reported values with improper values of saturation magnetization (Ms ), remnant magnetization (Mr ), and Mr/Ms ratio. To correct the measured VSM hysteresis loop, firstly, the paramagnetic-like slope of 0.0500–0.0735 G/Oe was subtracted until the flat at high fields was obtained. Then, up to 6% of magnetization value and demagnetizing factor (N) of 0.30-0.53 was applied to achieve similar hysteresis loops for all samples. The corrected (BH)max after all processes is around 86-95% of the reported value. Moreover, by examining the samples with different packing densities, it was found that the loose-packed samples exhibit hysteresis distortion, which could be caused by an unwanted magnetostatic interaction and degree of particle rotation of the powder.

Interactive visualization of forearm internal rotation angle in Tai Chi training

Modeling the visual features of the forearm internal rotation angle during Tai Chi training is difficult, and its accurate detection is lacking. To address this issue, this paper proposes an interactive visualization analysis method based on Harris corner detection and edge contour feature extraction to visualize and adjust the internal rotation of the forearm during Tai Chi training in real time. In the proposed method, the visual images of limb movement and forearm rotation during the Tai Chi training are collected as features, and the wavelet image denoising method is used to denoise the images to improve the signal-to-noise ratio of the output. Meanwhile, the image pixel uniform traversal method is used to continuously traverse the image subblocks to extract the edge contour features during the forearm internal rotation interaction. By means of superpixel feature decomposition and grayscale information superposition, the fitting effect of the forearm internal rotation angle is fed back, and based on this, the forearm internal rotation angle is modified to realize the interactive visual analysis of the forearm internal rotation angle. Experimental results show that, compared with existing methods, the interactive visualization performance of the proposed method is better. The proposed method can fit, track, and solve the rotation angle in real time; the required analysis training images are more accurate, and the Tai Chi training data detection and dynamic analysis abilities are improved.

Time-dependent two-dimensional translation of a freely rotating sphere in a viscoelastic fluid

This study examines the movement of a small freely rotating spherical particle in a two-dimensional trajectory through a viscoelastic fluid described by the Giesekus model. The fluid equations of motion in the inertialess limit and the Giesekus constitutive equation are expanded as a power series in the Weissenberg number, for which analytical solutions for velocity and pressure profiles at low order can be determined for the case of a steady-state flow. These steady solutions are then related to Fourier-transformed variables in frequency space through the use of correspondence relationships, allowing the analysis of time-dependent particle trajectories. The relative unsteadiness and nonlinearity of these time-dependent flows are quantified through a Deborah and Weissenberg number, respectively. The impact of changing these dimensionless parameters on the characteristics of the flow is discussed at length. We calculate the predicted rate of rotation of a small particle undergoing an arbitrary two-dimensional translation through a viscoelastic fluid, as well as the predicted correction to the force exerted on the particle arising from the interaction of particle rotation and translation. Finally, we calculate the angular velocity and total force including second-order corrections for particles executing a few specific trajectories that have been studied experimentally, as well as the predicted trajectory for a particle being directed by a known time-dependent forcing protocol.

Ultrasensitive measurement of angular rotations via a Hermite–Gaussian pointer

Exploring high sensitivity on the measurement of angular rotations is an outstanding challenge in optics and metrology. In this work, we employ the m n -order Hermite–Gaussian (HG) beam in the weak measurement scheme with an angular rotation interaction, where the rotation information is taken by another HG mode state completely after the post-selection. By taking a projective measurement on the final light beam, the precision of angular rotation is improved by a factor of 2 m n + m + n . For verification, we perform an optical experiment where the minimum detectable angular rotation improves 15 -fold with HG55 mode over that of HG11 mode, and achieves a sub-microradian scale of the measurement precision. Our theoretical framework and experimental results not only provide a more practical and convenient scheme for ultrasensitive measurement of angular rotations but also contribute to a wide range of applications in quantum metrology.

Degradation of dibutyl phthalate by ozonation in the ultrasonic cavitation-rotational flow interaction coupled-field: performance and mechanism.

Dibutyl phthalate (DBP) is present in hydraulic fracturing flowback and produced water. Degradation of DBP in aqueous by means of ozonation in ultrasonic cavitation-rotational flow interaction coupled-field (UC-RF coupled-field) was studied. The effect of ozone dosage, ozone intake flow, operating temperature, initial pH, DBP initial concentration, liquid flow rate, and ultrasonic power on the DBP removal was investigated. Results indicated that the DBP degradation rate was strongly influenced by the liquid flow rate and the ultrasonic power over the range investigated. HCO3- and Cl- revealed an inhibitory effect on the DBP removal. SO42- seemed to have no effect on DBP removal. The ozone utilization efficiencies in the UC-RF coupled-field were 2.77 and 1.13 times higher than those in the conventional microporous aeration (CMA) and rotating-flow microbubble aeration (RFMA), respectively. The DBP degradation rate was diminished in the presence of tert-butyl alcohol. Cavitation bubbles are considered as innumerable microreactors. Degradation of DBP by direct ozonation, hydroxyl radical (·OH) oxidation, high pressure, and high-temperature pyrolysis was demonstrated. Finally, a possible degradation pathway of DBP is obtained on the basis of the main reaction intermediates.

Topological excitations in rotating spin–orbit-coupled spin-1 Bose–Einstein condensates with in-plane gradient magnetic field

We investigate the topological excitations of rotating spin-1 ferromagnetic Bose–Einstein condensates with spin–orbit coupling (SOC) in an in-plane quadrupole field. Such a system sustains a rich variety of exotic vortex structures due to the spinor order parameter and the interplay among in-plane quadrupole field, SOC, rotation, and interatomic interaction. For the nonrotating case, with the increase of the quadrupole field strength, the system experiences a transition from a coreless polar-core vortex with a bright soliton to a singular polar-core vortex with a density hole. Without rotation but with a fixed quadrupole field, when the SOC strength increases, the system transforms from a central Mermin–Ho vortex into a criss-crossed vortex–antivortex string lattice. For the rotating case, we give a phase diagram with respect to the quadrupole field strength and the SOC strength. It is shown that the rotating system supports four typical quantum phases: vortex necklace, diagonal vortex chain cluster, single diagonal vortex chain, and few vortex states. Furthermore, the system favors novel spin textures and skyrmion excitations including an antiskyrmion, a criss-crossed half-skyrmion–half-antiskyrmion lattice, a skyrmion-meron necklace, a symmetric half-skyrmion lattice, and an asymmetric skyrmion-meron lattice.

Chiral effects in classical spinning gas

We consider a statistical mechanics of rotating ideal gas consisting of classical non-relativistic spinning particles. The microscopic structure elements of the system are massive point particles with a nonzero proper angular momentum. The norm of proper angular momentum is determined by spin. The direction of proper angular momentum changes continuously. Applying the Gibbs canonical formalism for the rotating system, we construct the one-particle distribution function, generalising the usual Maxwell–Boltzmann distribution, and the partition function of the system. The model demonstrates a set of chiral effects caused by interaction of spin and macroscopic rotation, including the change of entropy, heat capacity, chemical potential and angular momentum.

Large Eddy Simulation of Yawed Wind Turbine Wake Deformation

Wind turbine wake redirection drawn by a yaw control has been proposed as a strategy to improve the performance of wind farms. However, the characteristics and the development of the curled wake structure deformed by the yaw action of the rotor are not well understood. In the present study, the structure of the wake behind a wind turbine imparted with various yaw angles subjected to uniform inflow was investigated using large-eddy simulation. The NREL 5MW reference wind turbine was modeled with an actuator disk with rotation to study the deformation process of the curled wake. The source of the vertical asymmetry in the wake deformation was found to be based on the interaction of global wake rotation and a counter-rotating vortex pair induced by the yaw angle. The yaw angle had a profound influence on the distortion of the wake and its trajectory, whose effect was naturally mitigated with downstream distance.

Molecular Zeeman interactions in NMR spectra of methyl groups.

Methyl groups in organic solids generally behave as uniaxial quantum rotors. The existing nuclear magnetic resonance (NMR) theory appears to be complete, capable of describing even the finest details of the temperature-dependent spectra of such objects. However, the once reported temperature effects in the carbon spectra of the C13-labeled methyl group in a single crystal of acetylsalicylic acid have still not been explained. As the temperature decreases, in the quartet corresponding to the rapid motional averaging regime, the inner lines first begin to broaden, but then, they narrow again, so that at 6K, a pattern similar to that at room temperature was observed. In the present work, these puzzling effects are explained quantitatively by invoking the molecular Zeeman (MZ) interaction. Like the spin-rotation (SR) interaction long known to occur in methyl groups, it engages the magnetic moments generated by their torsional motions. However, it has not been considered in NMR spectroscopy until now. This is a surprising situation because in the magnetic fields currently used in NMR spectroscopy, the MZ interaction is orders of magnitude stronger than the (magnetic field independent) SR effects.

The C(2)[formula omitted] state in Rb2. Observation and deperturbation

We report a systematic study of the C(2)1Πuelectronic state in rubidium dimer, observed in polarization labelling spectroscopy experiment through the C ← X1Σg+ transitions recorded under rotational resolution in two isotopologues 85Rb2 and 85Rb87Rb. Regularity of the vibrational progressions was distorted by numerous interactions with the surrounding 21Σu+, 23Πuand 33Σu+states. Deperturbation was performed by coupled-channels analysis taking into account spin–orbit and rotational interactions. Potential energy curves and parameters describing the off-diagonal matrix elements were determined as functions of internuclear distance. About 3000 line frequencies from the present study are reproduced with a standard deviation of 0.07 cm−1, in agreement with the experimental accuracy. Along with this, the model is consistent with all high resolution experimental data on the involved electronic states, available in the literature.

High resolution spectroscopy of the [formula omitted] band of the [formula omitted]ClO2 free radical: Spin–rotation–vibration interactions

The high resolution spectrum of the ν1+ν3 band of the 35ClO2 free radical was recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer and theoretically analysed with an improved theoretical basis including the reduced effective spin–rotation Hamiltonian (which takes into account sixth order operators describing spin–rotational interactions) and a newly created computer code ROVDES for the ro–vibrational spectra of open–shell free radicals. About 2600 spin–ro–vibrational transitions with the values Nmax=59 and Kamax=17 (being about 2.4 times higher in comparison with the number of assigned transitions known in the literature) were assigned to the ν1+ν3 band of 35ClO2 and 1049 spin–ro–vibrational energies (produced only from unblended non–saturated and not very weak experimental lines) of the (101) upper vibrational state were obtained. A set of 30 varied parameters of the effective spin–rotation–vibration Hamiltonian of the (101) vibrational state (vibrational energy, 17 rotational and centrifugal distortion parameters and 12 are spin–rotational ones) was determined from the weighted fit of parameters of the effective spin–rotational Hamiltonian in A-reduction and Ir-representation. The obtained set of parameters reproduces the initial 1049 “experimental” upper state energies with the drms=2.5×10-4 cm−1 which is close to the experimental uncertainty of the recorded spectra and is almost 70 times higher in comparison with the analogous reproduction of the same initial upper energies with the use of parameters from (J.Mol.Spectrosc.,158,347-356(1993)).

Synthesis of Aza[n]helicenes (n = 4-7) via Photocyclodehydrochlorination of 1-Chloro-N-aryl-2-naphthamides.

A series of aza[n]helicenes (n = 4-7) was synthesized using a photocyclodehydrochlorination of 1-chloro-N-aryl-2-naphthamides as a general synthetic procedure introducing the nitrogen atom to the third ring of the helicene framework. The effect of the nitrogen presence in the helicene skeleton on the physicochemical properties of the prepared aza[n]helicenes was studied and compared to those of the parent carbo-analogues. The insertion of a nitrogen atom into the outer edge of the helicene molecule has a severe impact on certain physicochemical properties such as optical rotation, electrostatic potentials, and intermolecular interactions. On the other hand, some other properties such as UV/vis, fluorescence, and phosphorescence spectra remained almost unaffected when compared to the parent carbohelicenes. A nitrogen atom can be also used for further derivatization, which can lead to further modification of helicene properties, as manifested here in the fluorescence changes induced by protonation.

Long Term Effects of Tillage–Crop Rotation Interaction on Soil Organic Carbon Pools and Microbial Activity on Wheat-Based System in Mediterranean Semi-Arid Region

Conservation agriculture based on no-tillage (NT) and crop rotation allows to enhance soil health. Based on data collected from long-term trials in a semi-arid region of Tunisia, results showed that NT increased significantly soil organic carbon stock (SOCS), soil microbial biomass carbon (SMBC), arbuscular mycorrhizal fungal (AMF) root colonization, and soil microbial respiration (CO2) at 0–20 cm topsoil layer compared to conventional tillage (CT). Moreover, triennial rotation (TRI), based on annual succession of Faba bean-Durum wheat-Barley, and biennial rotation (BI), based on annual succession of Faba bean-Durum wheat, increased significatively SMBC, AMF, and CO2. Likewise, a significant benefit of the two-way interactions Tillage × Rotation was observed. Furthermore, NT combined with TRI recorded the highest SOCS (2181 g C m−2), SMBC (515 mg C kg−1 soil), AMF (14%), and CO2 which is an indicator of soil microbial respiration (1071 mg CO2 kg−1 soil). The current results highlight the benefit adoption of minimum or (NT)combined with crop diversification on soil health.

Numerical experiments to help understand cause and effect in massive star evolution

ABSTRACT The evolution of massive stars is affected by a variety of physical processes, including convection, rotation, mass-loss, and binary interaction. Because these processes modify the internal chemical abundance profiles in multiple ways simultaneously, it can be challenging to determine which properties of the stellar interior are primarily driving the overall evolution. Building on previous work, we develop a new modelling approach called snapshot that allows us to isolate the key features of the internal abundance profile that drive the evolution of massive stars. Using our approach, we compute numerical stellar structure models in thermal equilibrium covering key phases of stellar evolution. For the main sequence, we demonstrate that models with the same mass and very similar surface properties can have different internal distributions of hydrogen and convective core masses. We discuss why massive stars expand after the main sequence and the fundamental reasons for why they become red, blue or yellow supergiants. For the post-main sequence, we demonstrate that small changes in the abundance profile can cause very large effects on the surface properties. We also discuss the effects that produce blue supergiants and the cause of blue loops. Our models show that massive stars with lower metallicity tend to be more compact due to the combined effect of lower CNO abundances in the burning regions and lower opacity in the envelope.

Effects of a high Reynolds number and rotation on the leading-edge heat transfer of a ribbed cooling channel with a cross-section consisting of a semicircle and a rectangle

Owing to the recent increase in the demand for gas turbines with increased thrust, efficiency, and performances, the optimization of the heat transfer performance is necessary. In this study, the heat transfer performance in a combined-shaped cooling channel with angled ribs was investigated experimentally. The channel cross-section (Dh = 18.23 mm) was composed of a semicircle and a rectangle, which is appropriate for simulating a turbine blade leading-edge. The rib angle was 60° and staggered, and it was placed on the trailing and leading surfaces with a pitch-to-height ratio (P/e) of 10.0. The effects of the Reynolds number and rotation were studied. The Reynolds number varied from 18000 to 63000, and the rotation number ranged from 0 to 0.8. The results revealed that in the non-rotating ribbed channel, the Nu/Nu0 ratio along the streamwise direction first increased and then decreased slightly after a peak, followed by an increase. The Nu/Nu0 ratio reached a maximum of 6.4 in the rotating channel, and was greater than that in the non-rotating channel by a factor of 1.79. It was found that owing to the rib–rotation interaction, the Nu/Nus ratio exhibited different trends with an increase in Ro at different measurement points with small and large radii. The findings can serve as the basis for the development of high-performance gas turbines with increased thrust and efficiency.

Scrutinization of thermodynamic second law for the steady flow of couple stress nanofluid in an inclined microchannel by varying thermal conductivity

AbstractThis study comprises the flow of Ti6Al4N nanoparticle alloy allowed to flow within the microchannel kept at a certain angle. Engine oil is the base fluid in which nanodimensional particles are immersed. The flow is caused by the influence of linear and exponential heat sources. The microchannel is a permeable media with the suction/injection at the microchannel extremes. During the flow, the impact of the microstructure of these particles is concerned, thus reporting the rotational interaction amidst the particles. The obtained nonlinear equations are solved using the effective numerical method, namely, finite difference code improved by using the Lobatto IIIA formula and the findings are discussed using the graphs. The results attained claim that linear and exponential space‐dependent heat source parameter has augmented the thermal profile. Also, consideration of the couple stress of the fluid is known to retard the flow.

Mono- and di-deuterated ammonias: Far-infrared spectra and spectroscopic parameters in the ground state

Transitions of NH2D and ND2H have been detected in the high resolution spectrum of 14ND3 recorded at unapodized resolution of 0.00096 cm−1 in the region 60–600 cm−1 using the Bruker IFS 125 Fourier transform spectrometer located at the synchrotron far-infrared beamline, Canadian Light Source. In this study we report on the observation and analysis of the spectrum for the ground state of NH2D and ND2H. 2153 rotation and rotation-inversion transitions, with J up to 24, were assigned for NH2D, and 3214 transitions, with J up to 28, for ND2H. The newly assigned transitions, together with those present in the literature, were fitted on the basis of a Watson-type S reduced Hamiltonian using the IIIr and IIIl representations for NH2D and ND2H, respectively. The model Hamiltonian includes terms up to the 10th power of the angular momentum and vibration–rotation interaction terms between the inversion states. Precise and extended sets of spectroscopic effective parameters were derived for both isotopologues as results of least squares weighted fit procedures that reproduce the transition wavenumbers at experimental accuracy.