Symmetric Pattern Research Articles

Idempotent cellular automata and their natural order

Motivated by the search for idempotent cellular automata (CA), we study CA that act almost as the identity unless they read a fixed pattern p. We show that constant and symmetrical patterns always generate idempotent CA, and we characterize the quasi-constant patterns that generate idempotent CA. Our results are valid for CA over an arbitrary group G. Moreover, we study the semigroup theoretic natural partial order defined on idempotent CA. If G is infinite, we prove that there is an infinite independent set of idempotent CA, and if G has an element of infinite order, we prove that there is an infinite increasing chain of idempotent CA.

The Role of (Re)Syllabification on Coarticulatory Nasalization: Aerodynamic Evidence from Spanish

Tautosyllabic segment sequences exhibit greater gestural overlap than heterosyllabic ones. In Spanish, it is presumed that word-final consonants followed by a word-initial vowel undergo resyllabification, and generative phonology assumes that canonical CV.CV# and derived CV.C#V onsets are structurally identical. However, recent studies have not found evidence of this structural similarity in the acoustics. The current goal is to investigate anticipatory and carryover vowel nasalization patterns in tautosyllabic, heterosyllabic, and resyllabified segment sequences in Spanish. Nine native speakers of Peninsular Spanish participated in a read-aloud task. Nasal airflow data were extracted using pressure transducers connected to a vented mask. Each participant produced forty target tokens with CV.CV# (control), CVN# (tautosyllabic), CV.NV# (heterosyllabic), and CV.N#V (resyllabification) structures. Forty timepoints were obtained from each vowel to observe airflow dynamics, resulting in a total of 25,200 datapoints analyzed. Regarding anticipatory vowel nasalization, the CVN# sequence shows an earlier onset of nasalization, while CV.NV# and CV.N#V sequences illustrate parallel patterns among them. Carryover vowel nasalization exhibited greater nasal spreading than anticipatory nasalization, and vowels in CV.NV# and CV.N#V structures showed symmetrical nasalization patterns. These results imply that syllable structure affects nasal gestural overlap and that aerodynamic characteristics of vowels are unaffected across word boundaries.

Therapeutic Effect of Alpha Lipoic Acid in a Rat Preclinical Model of Preeclampsia: Focus on Maternal Signs, Fetal Growth and Placental Function.

Chronic hypertension is a major risk factor for preeclampsia (PE), associated with significant maternal and neonatal morbidity. We previously demonstrated that pregnant stroke-prone spontaneously hypertensive rats (SHRSP) display a spontaneous PE-like phenotype with distinct placental, fetal, and maternal features. Here, we hypothesized that supplementation with alpha lipoic acid (ALA), a potent antioxidant, during early pregnancy could ameliorate the PE phenotype in this model. To test this hypothesis, timed pregnancies were established using 10 to 12-week-old SHRSP females (n = 19-16/group), which were assigned to two treatment groups: ALA (injected intraperitoneally with 25 mg/kg body weight ALA on gestation day (GD1, GD8, and GD12) or control, receiving saline following the same protocol. Our analysis of maternal signs showed that ALA prevented the pregnancy-dependent maternal blood pressure rise (GD14 blood pressure control 169.3 ± 19.4 mmHg vs. 146.1 ± 13.4 mmHg, p = 0.0001) and ameliorated renal function, as noted by the increased creatinine clearance and improved glomerular histology in treated dams. Treatment also improved the fetal growth restriction (FGR) phenotype, leading to increased fetal weights (ALA 2.19 ± 0.5 g vs. control 1.98 ± 0.3 g, p = 0.0074) and decreased cephalization indexes, indicating a more symmetric fetal growth pattern. This was associated with improved placental efficiency, decreased oxidative stress marker expression on GD14, and serum soluble fms-like tyrosine kinase 1 (sFlt1) levels on GD20. In conclusion, ALA supplementation mitigated maternal signs and improved placental function and fetal growth in SHRSP pregnancies, emerging as a promising therapy in pregnancies at high risk for PE.

Fac-[M(CO)3] (M = Mn or Re)-based capped metallacalix[3]arenes

A flexible tritopic ligand, 1,3,5-tri(5,6-di-(methoxycarbonyl)-benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene (Tebim) was designed, synthesized and characterized. Six neutral heteroleptic fac-[M(CO)3]-based capped metallacalix[3]arenes with/without six or twelve ester decorated motifs were synthesized via one-pot approach using M2(CO)10 (M = Mn or Re), rigid angular bidentate ligand (benzimidazole (H-bim) or 5,6-di-(methoxycarbonyl)-benzimidazole (H-ebim)), and tritopic ligand (1,3,5-tri(benzimidazol-1-ylmethyl)-benzene (Tbim) or Tebim). All capped metallacalix[3]arenes are characterized using FT-IR, 1H NMR spectroscopy and mass spectrometry. The 1H NMR spectra for all the complexes displayed a simple and symmetrical pattern with characteristic upfield and downfield shifts for the protons of both the coordinated ligands, which signifies that synthesized capped metallacalix[3]arenes retains the structural framework in the solution. Further, the molecular structures of 1 and 3b were confirmed by single crystal X-ray diffraction analysis.

The use of Cauchy-type singular integrals over neighboring intervals to compute induced slip in displaced faults

We present expressions to compute the inverse of a Cauchy-type singular integral equation representing the relation between a double-peaked Coulomb stress in a fault or fracture and the resulting slip gradient in two distinct collinear slip patches. In particular we consider a situation where the patches are close enough to account for the influence of the slip gradient in one patch on the slip-induced shear stress in the other patch and vice versa. This situation can occur during depletion-induced or injection-induced fault slip in subsurface reservoirs for, e.g., natural gas production, hydrogen or CO2 storage, or geothermal operations. The theory for a single slip patch is well-developed but the situation is less clear for a configuration with two patches although the monographs of Muskhelishvili (1953) and Weertman (1996) provide earlier results. We show that the general inverse solution for the coupled two-patch problem requires six auxiliary conditions to ensure six physical requirements: boundedness of the slip gradient at the four end points of the slip patches and vanishing of the integrals of the slip gradient over the patches. Mathematically, the presence of two additional conditions, as compared to earlier formulations, corresponds to two undetermined coefficients in the general solution of the governing integral equation. Numerical simulation confirms that at least one of these is always non-zero in the coupled situation. For a coupled double-patch case with a symmetric pre-slip Coulomb stress pattern, the general inverse solution requires three auxiliary conditions. Moreover the conditions for the asymmetric case may be reduced to a set of four again, but these are different from the sets of four obtained earlier by Muskhelishvili (1953) and Weertman (1996). We illustrate the theory with a numerical example in which the evaluation of the Cauchy integrals is performed with a modified version of augmented Gauss–Chebyshev quadrature that relies on analytical inversion.

ANALISIS DATA PANEL TRANSMISI HARGA BERAS DI PROVINSI LAMPUNG

The aims of this research are to examine the transmission of rice prices from the producer (miller) level to the consumer vertically, and to analyze the factors that influence determination of rice princes at the producer (miller) level in Lampung Province. The type of method applied in this research was descriptive research with quantitative approach. Data analysis was carried out using panel data from January 2020 to December 2022 fron 15 regencies/cities in Lampung Province. In addition, the data in this research was also analyzed by using Asymmetric Error Correction Model (AECM) and Ordinary Least Squares (OLS). The results obtained in this research indicate that a symmetrical transmission pattern of rice prices in the short term and an asymmetrical transmission pattern in the long term are occured in Lampung Province. Factors that influence the price of rice at the producer (miller) level in Lampung Province are the consumer price of rice, the price of imported rice, rice consumption, and the producer price of corn.Key words: economic valuation, travel cost method, visitor satisfaction

Quantitative Characterization of the Perforation Behaviour of Direct Recycled Aluminum Alloy 6061 Plates Subjected to High-Velocity Impact

This study aims to establish the perforation behaviour of direct recycled AA6061 to help establish the properties of the current most optimized direct recycled AA6061 through the hot press forging technique. This was achieved by subjecting direct recycled AA6061 plates of varying thickness to high-velocity impacts using a single-stage gas gun setup. The impactor is a hemispherical steel projectile of 13mm in length and 8.5mm in diameter. Plates of 3,4,5 and 10mm thickness were tested at velocities ranging from 120 m/s to 402 m/s. The deformation profiles of the impacted plates were captured and analyzed to quantitatively establish the perforation behaviour of recycled AA6061 plates. The plates showed irregular and non-axis symmetric patterns of deformation hinting the material exhibits anisotropic properties. The changes in the deformation profile were investigated in relation to changes in impact velocities and plate thickness were made to understand how they impact the profile. The deformation area was observed to be decreasing when the bullet impact velocity was increased. Higher velocity impact events lead to more material ejection from the plate in the form of fragmentation. Additionally, the deformation zone was observed to be getting smaller with an increase in the thickness of the plate. Thicker plates were found to have more fragmentation compared to thinner plates. Ductile failure characteristics such as petal formation and plugging were observed along with brittle characteristics such as fragmentation and conal fractures. Lower-velocity impacts lead to more energy absorbed by the target plates. Thicker plates observed more of the bullet’s energy. Through experimentation, the deformation behaviour of the directly recycled AA6061 material was established. This data can be used as a base for further research into the material’s behaviour characterisation.

Studying the effect of polycarbonate sheet integration on glass fiber‐epoxy hybrid composite performance for automotive applications

AbstractThermoplastic polycarbonate provides minimal structural weight and ductility and is a recyclable material. However, investigation of the characteristics of hybrid composites reinforced with woven glass and polycarbonate sheets is limited. This current study investigated the effect of integration of polycarbonate sheets on glass fiber‐epoxy hybrid composite performance. Non hybrid laminate was fabricated from eight layers of woven glass fiber impregnated with epoxy resin (NG). However, the hybrid samples utilized various symmetric stacking patterns which were made by alternating two processed polycarbonate (PC) sheets with six layers of woven glass fiber embedded with epoxy matrix. The manufacturing was made using the hand layup procedure. Mechanical testing includes compressive, tensile, bearing, and hardness was performed on hybrid and non‐hybrid composites. The results showed that employing PC sheets instead of fibers affect the laminate's strength, ductility, bearing capacity, and hardness. Utilization of PC sheets reduces both compressive and tensile strength. However, an enhancement in tensile, compressive, and bearing failure strain was achieved by 2.5%, 31.25% and 31.7%, respectively with hybrid composite having PC in the skin layers as compared with NG. The extent of failure damage is correlated with the position of the PC sheets in the tested samples.Highlights Novel hybrid composites of woven glass fiber and polycarbonate sheet as reinforcement with various stacking orders were successfully prepared by the hand lay‐up method. The compressive strain of hybrid PC samples are higher than NG sample. The hybrid PC composites showed an improved bearing strength and strain performance. The influence of sample configuration on the damage mechanisms has been investigated.

Flexible dual-mode ammonia-impedance sensing patch (FDP) based on Ti3C2Tx MXene/graphene material and symmetric structure

The pursuit of simple, cost-effective, and efficient flexible ammonia sensors is an area of keen interest. This study aimed to create a highly sensitive, affordable flexible sensing patch (FDP) for immediate ammonia and impedance monitoring. Using a laser direct writing technique, symmetrical graphene patterns were crafted onto commercial kapton tape. These patterns were folded in half, allowing the lower layer to serve as an impedance sensor and the upper layer as an electrode for ammonia detection. The modified Ti3C2Tx MXene solution was introduced as the sensitive layer in response to ammonia gas, and we also explored how varying thicknesses of this sensitive layer affected the response results. Notably, the results highlighted that FDPs with two thicknesses (50 μL solution) offered optimal ammonia detection. With a detection limit of 150 ppb, impressive sensitivity (18.08%/ppm), exceptional linearity (0.996), and stability within the 0.5 ppm–20 ppm range, the overall performance of the FDP surpassed that of most reported ammonia sensor devices based on graphene materials. FDP was able to better characterize the shelf life of lamb at a cost of no more than $1.5. This study provides solutions for rapid ammonia detection and food quality assessment.

Study on flow regimes and mixing of vortex-inducing T-jet reactors with staggered inlet channel

Improving the jet reactor's mixing performance is critical and challenging. In this paper, a new type of vortex-inducing T-jet reactor proposed by researchers is studied. By designing the staggered inlet structure of the T-jet reactor, the vortex is induced in the flow field in the mixing channel to improve the mixing effect. Flow regimes and mixing characteristics in the vortex-inducing T-jet reactor were investigated through numerical simulations (CFD) at 30 ≤ Re ≤ 600. Results show that the staggered inlet channel induces vortices successfully, and the engulfment flow regime occurs at lower Reynolds numbers, thus promoting the mixing. The generation and evolution of vortex structures in the reactor were focused on. It was found that in the unsteady engulfment flow, the two fluids cross each other, which makes the vortex structure constantly twist and merge, which greatly improves the mixing effect. At larger Reynolds numbers, many attached small vortices are generated around the central vortex structure, and these vortices are wound together with the high-speed rotation of the central vortex, avoiding the unsteady symmetric flow pattern with a poor mixing effect. Finally, it is found that the mixing performance of the vortex-inducing T-jet reactor is greatly improved under all regimes.

Symmetric and asymmetric Tricomi-Gaussian beams in a gradient-index medium

In this paper, the propagation dynamics of the Tricomi-Gaussian Beam (TGB) in a gradient-index medium is studied. Influences of various beam parameters, the gradient-refractive index coefficient, and vortices on the propagation of TGB are investigated thoroughly. The research is mainly on the transmission characteristics of TGB with different modes, including symmetric and asymmetric patterns. Notably, the manipulations of beam modes, propagation trajectory, and intensity distribution of TGB by varying beam parameters α and β are explored. In addition, the autofocusing properties of TGB under off-axis conditions are investigated, which could find potential applications in optical trapping, laser energy focusing, and photonic waveguiding.

CT reconstruction based 3D model of the digital cushion's blood supply in the hind foot of an African savanna elephant (Loxodonta africana).

Foot health is crucial for elephants, as pathological lesions of the feet are a leading cause of euthanasia in captive elephants, which are endangered species. Proper treatment of the feet, particularly in conditions affecting the digits and the digital cushion, requires a thorough understanding of the underlying anatomy. However, only limited literature exists due to the small population and the epidemiological foot diseases which often precludes many deceased elephants from scientific study. The aim of this study was to provide a detailed anatomical description of the blood supply to the African elephant's hindfoot. The healthy right hindlimb of a 19-year-old deceased female African savanna elephant was examined using computed tomography. Following a native sequence, 48 mL of barium-based contrast agent was injected into the caudal and cranial tibial arteries, and a subsequent scan was performed. The images were processed with 3D Slicer software. The medial and lateral plantar arteries run in a symmetrical pattern. They each have a dorsal and a plantar branch, which reach the plantar skin before turning toward the axial plane of the sole to reach the digital cushion from the proximal direction. An accurate 3D model of the arteries and the bones of the foot, a set of labeled images and an animation of the blood supply have been created for ease of understanding. In contrast to domestic ungulates, the digital cushion of the hindlimb is supplied differently from that of the forelimb. The lack of large vessels in its deeper layers indicates a slow regeneration time. This novel anatomical information may be useful in the planning of surgical interventions and in emergency medical procedures.

Design of a Wireless Monitoring System for Vibration Characteristics of the Wheeled Tractor at Idle Speeds

To enhance the precision and efficiency of the tractor-failure-rate and equipment-quality inspection, the present study introduces a wireless rapid detection method for assessing tractor quality. For this study, which was based on the symmetrical structural characteristics of tractors, we designed a magnetic suction accelerometer. The test system was composed of a wireless router, a magnetic suction accelerometer sensor, a data-acquisition terminal, and other components. This test system aimed to test the equipment quality of the tractor at idle speed before leaving the factory. The experiment found that the vibration characteristics of the tractor had a symmetrical pattern on the left and right sides of the front and rear axle at idle. When the idle speed of the tractor was 800 r/min and 1000 r/min, the predominant vibration direction of both sides of the front axle of the tractor was the Y direction, while the predominant vibration direction of the rear axle was the Z direction. The experimental results showed that the proposed wireless rapid detection method of tractor quality and the designed acceleration sensor had good testing accuracy. The present study could provide a novel rapid detection method for the failure detection of power machinery in the agricultural field and for inspection before leaving the factory. The implementation of the method could improve the detection efficiency, and reduce the detection cost and the incidence of failure during actual use.

Morphological Features Among Gaussian, Sagittal, and Tangential Curvature Maps in Normal and Keratoconus Eyes Using Anterior Segment Optical Coherence Tomography.

To investigate and compare the morphological features and differences among Gaussian, Sagittal, and Tangential anterior corneal curvature maps obtained with an anterior segment optical coherence tomographer combined with a Placido disc MS-39 device in keratoconus (KC) and normal eyes. Prospective, cross-sectional study including 37 KC and 51 healthy eyes. The pattern of astigmatism and maximum keratometry (Kmax), keratometry at the thinnest point (Ktp) and 2 mm diameter (K 2mm ), and inferior-superior dioptric asymmetry values were obtained and calculated from Gaussian, Tangential, and Sagittal curvature maps using the MS-39 (CSO). In KC eyes, an asymmetric bowtie pattern was observed in 64.86% (24/37), 64.86% (24/37), and 0% in the Sagittal, Tangential, and Gaussian maps, respectively. In normal eyes, 51.0% (26/51), 51.0% (26/51), and 0% showed a symmetric bowtie pattern in the Sagittal, Tangential, and Gaussian maps, respectively. There was a significant difference for the variables Kmax, Ktp, and K 2mm inferior among the Gaussian, Tangential, and Sagittal maps in both normal and KC groups. Sensitivity discriminating between normal and KC eyes was 100%, 97.3%, and 90.9% and specificity was 94.1%, 100%, and 100% for Kmax coming from the Tangential, Gaussian, and Sagittal maps, respectively. Gaussian maps displayed significantly different morphological features when compared with Sagittal and Tangential maps in normal and KC eyes. Anterior curvature maps from Gaussian maps do not show the morphological pattern of symmetric bowtie in normal eyes nor asymmetric bowtie in KC eyes. Kmax from Gaussian maps are more specific, however less sensitive than Tangential maps in discriminating KC from normal eyes.

Examining sources of language production switch costs amongst Tibetan-Chinese-English trilinguals

ABSTRACT The present study tested whether the switch costs of production-based language switching tasks by trilinguals are due to competition from outside language schemas or from within language systems. We recruited 90 Tibetan-Chinese-English trilinguals in 10th grade in a Tibetan middle school in China to name digits and number words using different stimuli valence. The study was divided into three experiments, one for each combination of two languages possible amongst Tibetan, Chinese and English. We observed the switch cost symmetrical patterns in the three experiments. The results suggest that the sources of switch cost are partially from outside competition between language schemas and partially from within language system. These results may contribute to our understanding of the language control mechanism between production-based and comprehension-based language switching tasks and language control mechanism of trilinguals with three orthographically different languages.

Colossal c-Axis Response and Lack of Rotational Symmetry Breaking within the Kagome Planes of the CsV_{3}Sb_{5} Superconductor.

The kagome materials AV_{3}Sb_{5} (A=K, Rb, Cs) host an intriguing interplay between unconventional superconductivity and charge-density waves. Here, we investigate CsV_{3}Sb_{5} by combining high-resolution thermal-expansion, heat-capacity, and electrical resistance under strain measurements. We directly unveil that the superconducting and charge-ordered states strongly compete, and that this competition is dramatically influenced by tuning the crystallographic c axis. In addition, we report the absence of additional bulk phase transitions within the charge-ordered state, notably associated with rotational symmetry breaking within the kagome planes. This suggests that any breaking of the C_{6} invariance occurs via different stacking of C_{6}-symmetric kagome patterns. Finally, we find that the charge-density-wave phase exhibits an enhanced A_{1g}-symmetric elastoresistance coefficient, whose large increase at low temperature is driven by electronic degrees of freedom.

Closing a conceptual gap in race perception research: A functional integration of the other-race face recognition and "who said what?" paradigms.

White people confuse Black faces more than their own-race faces. This is an example of the other-race effect, commonly measured by the other-race face recognition task. Like this task, the "Who said what?" paradigm uses within-race confusions in memory, but to measure social categorization strength. The former finds a strongly asymmetrical pattern of interrace perception, the other-race effect, yet the latter usually finds symmetrical patterns (equally strong categorization of own-race and other-race faces). In a "Who said what?" meta-analysis, racial categorization and individuation across races were only weakly asymmetrical (Study 1, n = 2,669). We aimed to resolve this empirical misalignment. As tested in other-race face recognition tasks, the weak asymmetry was not due to the limited number of portrait stimuli (Study 2, N = 99) nor to the longer duration of stimulus presentation in the "Who said what?" task (Study 4, n = 358). Pairing portraits with statements reduced the other-race effect (Study 3, n = 126). Showing each portrait repeatedly also reduced the other-race effect (Study 4, n = 358; Study 5, n = 470) but did not decrease infrahumanization of Black portraits (Study 6, n = 487). Consequently, presenting portraits only once in the "Who said what?" paradigm (Study 7, N = 112) resulted in strong interrace categorization and individuation asymmetries. This finding bridges a central conceptual gap between the other-race effect and social categorization strength. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The role of developmental factors in hypoplasia of deciduous teeth and treatment specifics in pediatric dental practice

Relevance. Congenital and systemic diseases can lead to developmental errors in the enamel organ, resulting in anomalies such as enamel hypoplasia. The high prevalence of these defects illustrates the vulnerability of teeth to changes in the intrauterine and postnatal environments. Enamel hypoplasia contributes to the development of caries and tooth wear by making enamel thinner, more retentive to dental plaque, and less resistant to acid degradation compared to normal enamel. Surfaces of the affected hard tissues are smooth and exhibit a symmetric distribution pattern. The occurrence of enamel hypoplasia in children is a significant factor in the development of caries; thus, they require comprehensive treatment and ongoing preventive care by a pediatric dentist.Purpose. To analyze the impact of factors contributing to the development of deciduous teeth hypoplasia in children, on the frequency of this condition and the specifics of its treatment by a pediatric dentist.Materials and Methods. The study involved the examination and treatment of children aged 4-12 at the Dental and Implantology Department of Kazan (Volga Region) Federal University over a 12-month period. Out of 972 children, 67 were diagnosed with systemic enamel hypoplasia. A questionnaire was developed for statistical research, and data were processed using Statistica 7.0 software Statistica 7.0 (StatSoft, США).Results. The survey revealed chronic diseases in 16.42% of mothers. During pregnancy, 68.6% of the mothers visited a dentist once, and 31.3% visited two to three times. Most mothers experienced early pregnancy toxemia—67% in the first half and 58.2% in the second half of the pregnancy. Additionally, 50.7% suffered from acute respiratory viral infections and influenza, and 25.4% had gastrointestinal diseases. Feeding practices involved breastfeeding in 68.7% of cases and artificial feeding in 31.3% (up to 3 months – 16.4%, up to 1 year – 64.1%, up to 2 years – 19.4%). Examination of the oral cavity in 67 children with systemic hypoplasia revealed a spotted form in 79.1% of cases and a purely destructive form in 20.9% of cases. Contemporary conservative dentistry emphasizes minimally invasive approaches to the treatment of such dental defects.Conclusion. The study of deciduous tooth hypoplasia in children highlighted the importance of the health status of the expectant mother and timely sanitation of the oral cavity. Particular attention should be paid to maternal infectious diseases, specifically influenza and ARVI. The findings underscore the need for preventive measures against temporary tooth hypoplasia from the onset of pregnancy planning to enhance the dental well-being of children.

Symmetrization of quasi-regular patterns with periodic tilting of regular polygons

AbstractComputer-generated aesthetic patterns are widely used as design materials in various fields. The most common methods use fractals or dynamical systems as basic tools to create various patterns. To enhance aesthetics and controllability, some researchers have introduced symmetric layouts along with these tools. One popular strategy employs dynamical systems compatible with symmetries that construct functions with the desired symmetries. However, these are typically confined to simple planar symmetries. The other generates symmetrical patterns under the constraints of tilings. Although it is slightly more flexible, it is restricted to small ranges of tilings and lacks textural variations. Thus, we proposed a new approach for generating aesthetic patterns by symmetrizing quasi-regular patterns using general k-uniform tilings. We adopted a unified strategy to construct invariant mappings for k-uniform tilings that can eliminate texture seams across the tiling edges. Furthermore, we constructed three types of symmetries associated with the patterns: dihedral, rotational, and reflection symmetries. The proposed method can be easily implemented using GPU shaders and is highly efficient and suitable for complicated tiling with regular polygons. Experiments demonstrated the advantages of our method over state-of-the-art methods in terms of flexibility in controlling the generation of patterns with various parameters as well as the diversity of textures and styles.

Numerical simulation of a double helix vortex structure in a tangential chamber

The paper investigates the flow structure in a tangential vortex chamber based on numerical simulation of unsteady turbulent flow by the LES method. The swirl flow in a cylindrical chamber was organized using 12 nozzles, supplying the flow tangentially. Three regimes were considered with different design swirl number S = 5.78, 8.67, and 17.34, which was varied by closing one or two nozzle rows. The unsteady computation shows the formation of a rotating double helix vortex structure in the regimes with S equal to 8.67 and 17.34, which is also verified by experimental observations. Several recirculation zones were formed in the tangential chamber near its axis, as well as along the wall at the lower part, and on the axis near the top lid. A dominant frequency was observed in the pressure pulsation spectrum, which increased with increasing swirl parameter, and for the S = 8.67 regime, it was approximately twice the rotational frequency of the double helix structure. In the course of rotation of the double helix structure, the vorticity redistributed between its branches from an approximately symmetric pattern and up to approaching a single-vortex structure at certain points in time.