Direction Of Inflow Research Articles

Propulsion performance of a cownose ray inspired robotic fish flapping pectoral fins near the ground

Cownose rays usually swim near the ground in the ocean and their swimming is inevitably affected by the ground effect. In this work, the hydrodynamic performance of cownose rays during near-ground swimming is investigated by experimental tests. The flapping of the pectoral fin of the robotic and numerical rays presents a high similarity in our kinematics comparison. We find a positive correlation between the flapping projected area in the direction of inflow and the thrust coefficient. The ground effect is found to have a great effect on the cownose rays swimming through our experiments and numerical simulations. The thrust and pitching moment increases as the near-substrate height decreases. Moreover, this ground effect is more prominent for symmetrical flapping compared with asymmetrical flapping. The flapping frequency and amplitude can also affect hydrodynamic performance significantly. This work may provide insight into the kinematics control of the pectoral fin flapping-based bio-inspired robots during near-substrate swimming.

Heat waves in Poland: The relations to atmospheric circulation and Arctic warming

AbstractFrom the beginning of the 21st century, the heat waves in Europe have become more frequent, severe and longer lasting, especially in the southern region. The longer duration of heat waves may be partly attributed to wave‐amplification, high‐amplitude waves in the mid‐latitudes, favouring the longer‐lasting blocking systems. The primary objective of the paper was to examine the long‐term changes of hot days and heat wave events and to identify the atmospheric circulation condition that prevails its occurrence. The other object was to investigate the correlations between hot days' occurrence in Poland and sea‐ice cover and sea surface temperature changes in the Arctic and its surroundings. Over the past few decades, Central and Southern Poland have experienced a considerable rise in maximum temperatures, which has led to an increase in the number of hot days. This increase is particularly prominent during the summer months (June, July and August) but also in May and September, which extends the hot season. Although heat waves have become more frequent and persistent since 2006, their mean intensity has remained unchanged. During all heat waves in Poland, the high‐pressure centre was located over the country or its close neighbourhood, mainly in the eastern sector but also in the south, southwest or over Scandinavia. The blocking systems were mainly related to the extended ridge of the Azores High, but also to strong blocking over the North Pole and Greenland reaching Scandinavia or anomalous high pressure in the East Arctic. The longest‐lasting heat waves were usually preceded by air masses advection from the Atlantic, but the highest potential temperature along the trajectories was observed for the southern direction of inflow. The growing number of hot days is statistically significantly related to the decreasing sea‐ice cover and increasing sea surface temperature in Arctic and Subarctic regions.

Performance evaluation of a light shelf with a folding reflector (LSFR) to improve daylighting performance

Recently, light shelves have been in the spotlight as a solution to the increasing lighting energy consumption in buildings, and various studies have confirmed their effectiveness. However, there is a lack of research on light shelves that operate according to the solar azimuth. To address this, this study proposes a light shelf with a folding reflector (LSFR) that operates in alignment according to the solar azimuth and validates its effectiveness through a testbed. The key findings are as follows. (1) The proposed LSFR is divided into three modules and becomes an inclined plane by moving the modules at both ends. Moreover, combined with light shelf angle control, the LSFR enables control over the direction of daylight inflow through light shelf reflection. (2) This study determines the optimal angle for a flat light shelf with angle control, highlighting the need to adjust the angle based on the external environment to enhance daylighting efficiency. (3) Upon implementing the optimal specifications, the LSFR reduces lighting energy consumption by an average of 49.5% and enhances the indoor uniformity ratio by 20.1% compared with Case 2 (flat light shelf with angle control). Particularly, the LSFR achieved a satisfactory 300 lx illumination without using additional lighting under the environmental conditions set in this study, which demonstrates the effectiveness of Case 3.

Твердые атмосферные осадки в г. Мурманске и его окрестностях

In the period from January 2, 2018 to December 30, 2022, a comprehensive study of solid atmospheric precipitation was carried out in Murmansk and its environs. Data were obtained on the concentration in freshly fallen snow of solid insoluble particles (9.19±0.51 mg/l) and their components: heavy metals (zinc – 60.1±9.8 ng/g, copper – 11.0±2.6 ng/g, lead – 3.28±0.18 ng/g, cadmium – 0.859±0.096 ng/g), nutrients (nitrates – 79±11 µg-at/l, nitrites – 1.02±0.14 µg-at/l, phosphates – 4.64±0.67 µg-at/l, silicates – 25±5 µg-at/l) and organic matter (21.2±2.2 mg/l), as well as the amount of polymer particles (fragments – 7766±1401 particles per liter, micro-fibers – 638±134 threads per liter, macro-fibers – 29±4 threads per liter). The relationship between the number of insoluble particles and the direction of air masses inflow was revealed. Air masses coming from the Barents Sea brought solid precipitation with less insoluble aerosols (including heavy metals, polymer particles and organic matter) than air masses coming from the continent. The amount of biogenic elements in solid atmospheric precipitation does not depend on the direction of inflow of air masses.

Diagnostic Method and Adaptability Analysis of Multiple Water Breakthroughs in Horizontal Well in Combined Well Pattern

The combined well pattern has been widely used in reservoir development, with a common pattern being a horizontal well in the center for oil production and multiple vertical wells around for water injection. For this type of well pattern, determining the horizontal well is affected by which injection wells, especially when the injecting water breaks through, accurately determining the direction of water inflow will provide an important basis for targeted water well measures. Based on the production performance data of horizontal wells, the semi logarithmic relationship curves of water-oil ratio, derivative water-oil ratio, and cumulative production were used for the first time to determine the breakthrough problem of water injection in the surrounding water injection wells of horizontal wells based on their response characteristics. The adaptability of this method under different influencing factors was analyzed. Introducing the parameter of cumulative production not only preserves the variation trend of the derivative of water-oil ratio with time, but also facilitates the processing of actual production data.

Breaking Correlation in the Inflow Parameters of Interstellar Neutral Gas in Direct-sampling Observations

We analyze the reasons for the correlation between the temperature, direction, and speed of the interstellar neutral gas inflow into the heliosphere, obtained in analyses of observations performed by an onboard Interstellar Boundary Explorer (IBEX) instrument, IBEX-Lo. We point out that this correlation is the combined result of the inability to measure the speed of the atoms that enter the instrument and the restriction of the observations to a short orbital arc around the Sun performed by the instrument during observation. We demonstrate that without the capability to measure the speed, but with the ability to perform observations along longer orbital arcs, or from at least two distant locations on the orbit around the Sun, it is possible to break the parameter correlation. This, however, requires the capability of adjusting the boresight of the instrument relative to the spacecraft rotation axis, such as that of the planned camera on board the Interstellar Mapping and Acceleration Probe (IMAP), IMAP-Lo.

Study on the effect of inflow conditions on wind flow acceleration in mountainous micro-topography

The acceleration of wind flow in mountainous areas can cause the destruction or collapse of transmission towers. The wind speed and direction of inflow have a significant impact on the flow acceleration in mountainous areas. The mountain terrain in the coastal area of Fujian was selected to study the influence of the inflow wind speed and direction on the acceleration effect. By analyzing the radar chart of the wind speed acceleration ratio of the monitoring points under 24 wind direction angles, the variation law of the wind speed acceleration ratio is consistent with the trend of the influence law obtained by the analysis of the surrounding terrain. The obtained simulation results are correct and credible, which can be used to correct the design wind speed of transmission lines in mountainous areas.

Nonuniform wind characteristics and buffeting response of a composite cable-stayed bridge in a trumpet-shaped mountain pass

Due to the spatial differences in wind fields in mountainous areas, it is an urgent problem to accurately estimate the buffeting response of long-span bridges in mountainous areas. In this paper, the spanwise variations in the mean and fluctuating wind characteristics of a bridge site are obtained based on a terrain wind tunnel test of a trumpet-shaped mountain pass. Additionally, the aerodynamic admittance function of a Π-shaped composite girder under different wind attack angles is measured in the wind tunnel. The buffeting response calculation theory considering the spanwise variations in the mean wind and fluctuating wind characteristics along the main girder is established. The influence of the nonuniform wind characteristics on the buffeting response of the main girder is analyzed. The results show that the spanwise variation in wind characteristics at the bridge site is affected by the direction of inflow and can be described by a quadratic polynomial. Nonuniform wind parameters have obvious effects on the buffeting response, and a nonuniform wind attack angle is a key factor affecting the buffeting response. It may not be appropriate to predict the buffeting response by using the single-point wind field observation results in mountainous areas.

Incomplete stent expansion in flow-diversion treatment affects aneurysmal haemodynamics: a quantitative comparison of treatments affected by different severities of malapposition occurring in different segments of the parent artery.

Incomplete stent expansion (IncSE) is occasionally seen in flow-diversion (FD) treatment of intracranial aneurysms; however, its haemodynamic consequences remain inconclusive. Through a parametric study, we quantify the aneurysmal haemodynamics subject to different severities of IncSE occurring in different portions of the stent. Two patient cases with IncSE confirmed in vivo were studied. To investigate a wider variety of IncSE scenarios, we modelled IncSE at two severity levels respectively located in the proximal, central, or distal segment of a stent, yielding a total of 14 treatment scenarios (including the ideal deployment). We examined stent wire configurations in 14 scenarios and resolved aneurysm haemodynamics through computational fluid dynamics (CFD). A considerable degradation of aneurysm flow-reduction performance was observed when central or distal IncSE occurred, with the maximal elevations of the inflow rate (IR) and energy loss (EL) being 10% and 15%. The underlying mechanism might be the increased resistance for flow to remain within the FD stent, which forces more blood to leak into the aneurysm sac. Counter-intuitively, a slight reduction of aneurysm inflow was associated with proximal IncSE, with the maximal further reduction of the IR and EL being 5% and 8%. This may be due to the disruption of the predominant parent-artery flow by the collapsed wires, which decreased the strength and altered the direction of aneurysmal inflow. The effects of IncSE vary greatly with the location of occurrence, revealing the importance of performing individualised, patient-specific risk assessment before treatment.

The variability of pollen concentrations at two stations in the city of Wroc\u0142aw in Poland

The aim of the study was to investigate the variability of Alnus and Corylus pollen concentrations at two stations located in the city of Wrocław, Poland—one at the city centre and the other 4 km from the city centre. Our goal was to compare measurements from these stations in relation to meteorology and land cover. We used Spearman’s correlation coefficient to investigate any dependence between meteorological factors and pollen concentration. Additionally, to check the relation between the direction of inflow of air masses and pollen concentration, we calculated the backward trajectories using the HYSPLIT model. The results have shown that despite the short distance between the stations, the characteristic of the pollen season is different for both stations (i.a. date of start and end of pollen season, duration of the season). The Spearman’s correlation coefficient between relative humidity and air temperature and pollen concentration was found to be statistically significant. The backward trajectories calculated with HYSPLIT suggested a different origin of air masses between stations for high-concentration episodes in the case of Alnus. Our study has shown that analysis of meteorological conditions and influence of air transport into pollen concentration makes it possible to ascertain the reasons for differences in pollen level at these two stations, both of which are located in the same climatological domain. The study also shows that the aerobiological condition may change significantly over a short distance, which is a major challenge, for example, for pollen emission, transport, and concentration modelling.

Symulacyjne modelowanie zjawiska dyspersji fizycznej obserwowanej w danych eksperymentalnych

The article concerns a practical solution of the problem connected with modeling of the physical dispersion phenomenon. It is a continuation of the author’s previous publications, in which calculations were made on both very simplified simulation models and the model of the real structure. In this article, an attempt was made to model the course of laboratory tests using a previously developed method of controlling the phenomenon of physical dispersion. Laboratory tests selected for modeling were carried out in the Department of Oil and Gas Reservoir Testing, which is located in the Krosno branch of the Oil and Gas Institute – National Research Institute. The said tests were carried out on the so-called long cores and concerned the displacement of oil with water. The method of modeling the course of these type of tests proposed in the article consisted in the use of a hybrid method of minimizing numerical dispersion and the extension of standard saturation equations by an additional element of physical dispersion. The article contains a brief description of the proposed method of controlling the size of the mixing zone of fluids and the results of application thereof. This article is a continuation of the author’s previous work and it contains only the most important mathematical formulas. For comparison purposes, the article also presents the results of modeling selected laboratory tests using numerical dispersion. This modeling consisted in modification of the blocks grid size, which resulted in mixing zones of the displacement fluid with the displaced fluid of various sizes. The results of performed simulations presented in the article, in the form of drawings and diagrams, showed the effectiveness of the applied method of limiting numerical dispersion (both for calculations of mobility with multi-point weighing in the direction of inflow, as well as double discretization grid) as well as the effects of using different values of physical dispersion parameters. In the article the results of matching the built simulation models with the results obtained in the laboratory were also presented (in the form of the results of the overall recovery of fluids).

The Impact of Climate Change and Strong Anthropopressure on the Annual Growth of Scots Pine (Pinus sylvestris L.) Wood Growing in Eastern Poland

Changes in annual tree ring width (TRW) and its size depends not only on the changing climate and natural stress factors such as extreme air temperatures, shortages in rainfall and excess rainfall during the growing season, but also on anthropogenic stress, including chemical compounds emitted to the atmosphere or lowering of the groundwater table caused by the operations of plants with high environmental impact. The purpose of this article is to assess the impact of meteorological conditions and anthropogenic factors on the size of annual growth of Scots pine tree-stands in the conditions of the climate of central-eastern Poland. On the basis of five created site chronologies in the vicinity of Zakłady Azotowe Puławy (nitrogen factories in Puławy) and using the moving correlation analysis and multiple regression analysis, a significant influence of temperature and precipitation conditions on the TRW size is proved. A significant, positive influence of air temperature on TRW was proved for the majority of chronologies created in the period of January–March, as well as in June, while it remained negative in May. The wide rings of Scots pines were formed when the precipitation of October and January (prior to the resumption of cambium activity) was lower than the average, and higher in April and in June–August. After including the anthropopressure factors in the regression equations, the description of the variability of the annual tree ring width was corrected. The coefficient of determination ranged from approx. 29% to even above 45% and was higher, on average by 10%, for all studied chronologies of Scots pine compared to the one calculated for constructed equations considering only meteorological conditions. The strength and direction of the impact of the independent variables (SO2, NH3, NOx) analysed on TRW mainly depended on the distance from the plants, as well as on the direction of inflow of industrial pollution to the stands examined. In light of the proven climate changes in central and eastern Poland, the growth conditions of pine stands will most likely deteriorate.

The impact of meteorological conditions on the concentration of alder pollen in Sosnowiec (Poland) in the years 1997\u20132017

The aim of the work was to compare the alder pollen seasons in the years 1997–2017 in Sosnowiec. The measurements of pollen concentration were taken with the volumetric method using Burkard’s apparatus. The impact of atmospheric conditions on the daily alder pollen grain concentration, the annual totals, and the duration of pollen seasons were studied. The dependency between each meteorological condition and different features of the alder pollen season was determined by using Pearson’s correlation coefficients, variance analysis with multiple comparison tests, and the linear regression model using backward elimination. It was proven that the temperatures directly preceding the pollination, i.e. the January and February temperatures as well as those from the period from 210 to 180 days preceding the beginning of the season, have the greatest impact on the beginning of the alder pollen season. The value of the daily alder pollen concentration in Sosnowiec showed a positive statistically significant correlation with the air temperature and sunshine duration and a negative correlation with the thickness of the snow cover and air relative humidity. The daily concentration also depended on the type of the weather front, direction of air mass inflow, and the type of the inflowing air mass. The season temperatures and the thermal conditions which were present in the summer of the preceding year impacted the annual totals (SPI) of the alder pollen grains.

Typy źródeł i ich rozmieszczenie na Babiej Górze (Zachodnie Karpaty) = Types of springs and their locations on Mount Babia Góra (Western Carpathians)

Hydrographical mapping carried out by the Author provided for a quantitative evaluation of the distribution of different types of springs located on the homoclinal ridge of Mount Babia Gora – at 1725 m a.s.l., the highest mountain in the Western Carpathians (Fig. 1), built of flysch sediment. Circulation of groundwater on ridge slopes modelled in different ways by landslides was analysed, with particular attention paid to the circulation of water in the deeply-fissured Magura Sandstone that forms the upper part of the massif, as well s the thick cover of colluvia (Figs. 2 and 3). The depth and distance of water circulation on different parts of the slopes were evaluated in relation to altitude, slope exposure, type of flysch rock and landslide topography. Six types of water-bearing sediment were distinguished, and their limits of occurrence identified. Magura Sandstone appeared to be the most water-retaining sediment, proving permeable down to depths of 100 m locally. Three classifications of springs were carried out, in line with geomorphological location (direction of groundwater inflow and means of circulation), type of water-bearing sediment, and local-scale distribution(in connection with landslide forms). Among the 873 springs located in the Polish part of Mt. Babia Gora, over 80% are slope located and can be regarded as descending springs. These include: rock springs (a), rock-debris springs (b), debris springs (c), and rock-mantle springs (d). Other springs occur on valley floors (e) and are also mostly of the descending type, though a few are ascending (mineral and thermal). Most springs are alimented by water flowing out from thick covers of colluvia. Within this group it proved possible to distinguish three subtypes of spring (b2, b3, b4 ) located in different segments of landslides (Fig. 4). Other divisions of springs were into single springs, lines of springs and series of springs (Fig. 5). The number of springs on the slopes of Mt. Babia Gora is similar to the number located at the foot of the mountain comprising lateral ridges and valley floors. Along a profile of altitude, the largest numbers of springs can be seen to be located at the heads of valleys, where the density on the northern slope exceeds 30 per. km-2 (Fig. 6). The density of springs on the southern slope in valleys located at high altitude is even greater. The determined distribution of springs down the altitudinal profile of Mt. Babia Gora allowed for delimitation of three hydrographical belts - of water alimentation, transit and accumulation, which are different from the hydrographical belts noted in the Western Beskidy and Tatra Mountains. The distribution of springs on Mount Babia Gora and their unusually high density are determined first and foremost by the landslide morphology of slopes.

Numerical study of bifurcating flow through sudden expansions: effect of divergence and geometric asymmetry

A numerical study of laminar flow through symmetric and slightly asymmetric sudden expansion, of expansion ratio 1:3, in channels with increasing cross section, is carried out using two different approaches - Conventional CFD and Lattice Boltzmann Method. The effect of divergence of walls of the channel, after a sudden expansion, on the symmetry of flow and recirculation is studied for various Reynolds numbers. It is seen that the angles of the walls play an active role in disrupting the symmetry of flow. For non-parallel walls, the symmetry breaking bifurcation phenomenon no longer exists and the loss of symmetry is a gradual process. The effect of asymmetry of geometry on flow is also studied by considering two types of asymmetry - First type is at the plane of expansion where the steps on either side are of unequal heights, while the second one deals the walls of the channel are at a different inclination with the direction of inflow. The present study reveals that small asymmetry impedes the sharp transition and thus smoothens the pitchfork bifurcation. Increased asymmetry finally leads to the unique solution of the governing Equations, indicating complete loss of bifurcation pattern.

The influence of the aortic valve angle on the hemodynamic features of the thoracic aorta.

Since the first observation of a helical flow pattern in aortic blood flow, the existence of helical blood flow has been found to be associated with various pathological conditions such as bicuspid aortic valve, aortic stenosis, and aortic dilatation. However, an understanding of the development of helical blood flow and its clinical implications are still lacking. In our present study, we hypothesized that the direction and angle of aortic inflow can influence helical flow patterns and related hemodynamic features in the thoracic aorta. Therefore, we investigated the hemodynamic features in the thoracic aorta and various aortic inflow angles using patient-specific vascular phantoms that were generated using a 3D printer and time-resolved, 3D, phase-contrast magnetic resonance imaging (PC-MRI). The results show that the rotational direction and strength of helical blood flow in the thoracic aorta largely vary according to the inflow direction of the aorta, and a higher helical velocity results in higher wall shear stress distributions. In addition, right-handed rotational flow conditions with higher rotational velocities imply a larger total kinetic energy than left-handed rotational flow conditions with lower rotational velocities.

Strontium isotope composition of Middle Miocene primary gypsum (Badenian of the Polish Carpathian Foredeep Basin): evidence for continual non‐marine inflow of radiogenic strontium into evaporite basin

AbstractStrontium isotope compositions of ancient sulphate deposits not only provide chemostratigraphic information but also offer insight into the system in which the evaporites precipitated. Primary gypsum from two Middle Miocene (Badenian) sections in southern Poland shows steadily higher 87Sr/86Sr ratios than those expected from a marine‐derived formation. The ratios are interpreted as the result of increasing inflow into the basin at the time of gypsum precipitation. Palaeogeographic reconstructions suggest that riverine runoff sources were situated in the West and East European platforms (to the north and east, respectively) and the Carpathians (to the south), which are mostly composed of Mesozoic sedimentary rocks; their dissolution cannot be responsible for the higher 87Sr/86Sr ratios recorded. We conclude that Archaean and Palaeoproterozoic igneous and supracrustal rocks of the Ukrainian Shield were the source of the higher 87Sr/86Sr ratios recorded in the Badenian primary gypsum. A distinctive decreasing trend of 87Sr/86Sr ratios from western Ukraine to southern Poland is explained by a consistent direction of brine inflow during gypsum crystallization (typical cyclonic circulation controlled by the Coriolis effect).

Energy saving on wastewater treatment plants through improved online control: case study wastewater treatment plant Antwerp-South

This work provides a case study on how activated sludge modelling and computational fluid dynamics (CFD) can help to optimize the energy consumption of a treatment plant that is already equipped with an advanced control based on online nutrient measurements. Currently, aeration basins on wastewater treatment plant Antwerp-South are operated sequentially while flow direction and point of inflow and outflow vary as a function of time. Activated sludge modelling shows that switching from the existing alternating flow based control to a simultaneous parallel feeding of all aeration tanks saves 1.3% energy. CFD calculations also illustrate that the water velocity is still sufficient if some impellers in the aeration basins are shutdown. The simulations of the Activated Sludge Model No. 2d indicate that the coupling of the aeration control with the impeller control, and automatically switching off some impellers when the aeration is inactive, can save 2.2 to 3.3% of energy without affecting the nutrient removal efficiency. On the other hand, all impellers are needed when the aeration is active to distribute the oxygen.

Three-Dimensional Echocardiographic Assessment of the Repaired Mitral Valve

This study examined the geometric changes of the mitral valve (MV) after repair using conventional and three-dimensional echocardiography. Prospective evaluation of consecutive patients undergoing mitral valve repair. Tertiary care university hospital. Fifty consecutive patients scheduled for elective repair of the mitral valve for regurgitant disease. Intraoperative transesophageal echocardiography. Assessments of valve area (MVA) were performed using two-dimensional planimetry (2D-Plan), pressure half-time (PHT), and three-dimensional planimetry (3D-Plan). In addition, the direction of ventricular inflow was assessed from the three-dimensional imaging. Good correlations (r = 0.83) and agreement (-0.08 +/- 0.43 cm(2)) were seen between the MVA measured with 3D-Plan and PHT, and were better than either compared to 2D-Plan. MVAs were smaller after repair of functional disease repaired with an annuloplasty ring. After repair, ventricular inflow was directed toward the lateral ventricular wall. Subgroup analysis showed that the change in inflow angle was not different after repair of functional disease (168 to 171 degrees) as compared to those presenting with degenerative disease (168 to 148 degrees; p<0.0001). Three-dimensional imaging provides caregivers with a unique ability to assess changes in valve function after mitral valve repair.

탄도만에 서식하는 낙지의 분포 특성

This study is to find out the distribution characteristic of Octopus minor in the Tando Bay on the southwest coast of Korea with conducting surveys from May of 2006 to April of 2007. Surveys were carried out at 20 stations on 2 and 3 tide time in the low speed of high tide at night and conducted during 30minutes (4 times fishing) per station. Catch per unit effort (CPUE) was estimated by total catch per 500hooks at each station. Monthly CPUE showed that they put highest in October, November, April and June at 10.4, 10.5, 9.4 and 7.7 individuals respectively. On the other hand, CPUE put lowest in January, the coldest month, and August, the hottest month, at 0.2 and 0.3 individuals respectively. As for geographical mantle length distribution, average mantle length ranged from 6.2cm to 7.3cm at stations near the tidal channels (St. 1, 4, 5, 6, 8, 9, 10, 13, 14, 15, 18, 19 and 20), and was smaller than 6.0cm at stations located inside of bay (St. 2, 3, 7, 11, 12 and 17). In terms of geographical distribution density, CPUE showed higher than 8.0 at St.4 in Changmaeri, St.8 in Taecheonri, St.13 near Seondo, St.18 in Naeri and St.14 in western part of Tando which are located near the main tidal channels. And distribution density showed low that CPUE was lower than 5.0 individuals at stations located inside of bay (St. 1, 3, 5, 6, 7, 11, 12, 16 and 20). Through the results, the difference of distribution density reflects that distribution of Octopus minor is affected by direction of current and inflow of pollutant from land in direct. Therefore, it is considered that bottom composition of tidal flat and distribution of live food are the crucial cause of identifying the distribution characteristics of Octopus minor. For this reason, it is judged to need additional research on it.