Ditch Width Research Articles

Effect of Parameters of Ditch Geometry on the Uniformity of Water Filling in Ship Lock Chambers

The design of ditch structures in ship locks has an important influence on reducing water flow energy, improving the uniformity of water filling in lock chambers, and reducing the force acting on mooring ships. Existing studies on the mechanisms of flow fields and mooring conditions under the influence of geometric structural changes in ditches are insufficient, and research is limited by the complexity of the problem. Based on OpenFOAM v8, a numerical simulation of the flow structure in a lock chamber was carried out. Taking into account the ditch width, ditch depth, and sill height of the side wall as the research variables, the influence of structural changes in four single ditches on the uniformity of water filling in the lock chamber is systematically discussed. The results show that under a complex boundary constraint, the flow is diffuse in the ditch and the lock chamber, and the filling of the lock chamber is not uniform. The uniformity of water filling is closely related to the arrangement of the ditch geometry. Through the comprehensive analysis of multiple factors, some parameter thresholds were obtained to provide theoretical guidance for ditch design. It is hoped that through improved design, allowing an increase in the uniformity of water filling, the lock chamber will reach a relatively optimal state.

高速耕作条件下土壤离散元参数标定

For the problem of lacking reliable values of soil parameters required for dynamic simulation analysis of soil under high-speed tillage, no-tillage soil was taken as the research object and its parameters were calibrated using the discrete element method in this study. The Edinburgh Elasto-Plastic Adhesion (EEPA) model was determined as the soil contact model by obtaining the loading force-deformation relationship through uniaxial sealing compression tests. The regression equation was established using Plackett-Burman test and quadratic orthogonal rotation test, and the interaction effects were analyzed. The measured values of the pile angle and strain were obtained through the pile angle test and the uniaxial seal compression test, and the optimal solution was carried out. Further, the simulated values and the measured values under the optimal parameters were compared and verified, the result showed that the error values were all less than 1%. Finally, the soil model was used for high-speed tillage simulation analysis, and the obtained soil particle displacement and groove width were compared with the measured values. It was found that the ditch width error value was 3.04% and the soil displacement was basically the same. This study proved that the contact model parameters were relatively reliable, which could provide theoretical reference for the dynamic characteristics of soil during high-speed cultivation of no-tillage soil.

Mesoscopic analysis of drag reduction performance of bionic furrow opener based on the discrete element method.

In order to study the dynamic interface mechanical behavior between soil and agricultural machinery and reveal the causes of tillage resistance, three kinds of bionic furrow opener were designed according to the characteristics of earthworm head surface curve, using the discrete element method to simulate and analyze the process of the furrow openers. The results showed that the order of ditching resistance from large to small is traditional opener, bionic corrugated opener, bionic ridgeline opener, bionic composite opener. With the same ditching speed, the drag reduction effect of the three bionic openers increases with the increase of the ditching depth. During the process of increasing the depth from 30 mm to 60 mm and 90 mm, the ditching resistance of the traditional opener increased from 11.56 N to 28.32 N and 48.61 N as well as the maximum drag reduction ratio increased from 5.58% to 7.20% and 8.93% for the bionic composite opener. With the same ditching depth, the bionic composite opener reached the highest drag reduction rate of all bionic openers when the speed is 100 mm/s, the value is 9.08%. The width of the ditch of the three bionic openers is smaller than that of the traditional opener. Bionic corrugated opener can improve the ditch height and reduce the ditch width,the corrugated structure creates a gap between the surface of the core and the particles, reducing the number of contact and contact area of the particles. The number of contact particles of the three bionic openers is smaller than that of the traditional opener. The bionic composite opener has the smallest force field and the soil disturbance caused by the core share surface is small, the soil is evenly distributed along the core surface. The discrete element simulation shows that the bionic opener can effectively reduce the ditching resistance and improve the quality of ditching, which provides a theoretical basis for subsequent research and optimization.

PITCH: A model simulating the transfer and retention of pesticides in infiltrating ditches and channel networks for management design purposes

Agricultural ditches are frequently included in the panel of landscape elements to be managed to minimize the negative impacts of agriculture on the environment, particularly water contamination. A new mechanistic model simulating pesticide transfer in ditch networks during flood events was developed for help in designing ditch management. The model considers pesticide sorption processes to soil, living vegetation and litter and is adapted to heterogeneous and infiltrating tree-like ditch networks, with a reach resolution. The model was evaluated with pulse tracer experiments conducted on two vegetated and litter-rich ditches and with two contrasting pesticides, namely, diuron and diflufenican. It appears necessary to consider exchange of only a small proportion of the water column with the ditch materials to achieve a good reproduction of the chemogram. The model simulates well the chemogram of diuron and diflufenican during calibration and validation (with Nash performance criteria values ranging from 0.74 to 0.99). The calibrated thicknesses of the soil and water layers contributing to the sorption equilibrium were very small. The former was intermediate between the theoretical transport distance by diffusion and the thicknesses usually considered in mixing models for pesticide remobilization by field runoff. The numerical exploration of PITCH showed that during flood events, retention in ditches is mainly due to adsorption of the compound by the soil and litter. Retention is thus driven by the corresponding sorption coefficients and by parameters controlling the mass of these sorbents such as ditch width and litter cover. The latter parameters can be modified by management practices. In some cases, infiltration can contribute significantly to pesticide removal from surface water and in return participate in soil and groundwater contamination. Finally, PITCH exhibits a consistent behaviour in predicting pesticide attenuation and is shown to be relevant for evaluating ditch management strategies.

Microgroove Cues Guiding Fibrogenesis of Stem Cells via Intracellular Force

Groove patterns are widely used in material surface modifications. However, the independent role of ditches/ridges in regulating fibrosis of soft tissues is not well-understood, especially the lack of linkage evidence in vitro and in vivo. Herein, two kinds of combinational microgroove chips with the gradient ditch/ridge width were fabricated by photolithography technology, termed R and G groups, respectively. In group R, the ridge width was 1, 5, 10, and 30 μm, with a ditch width of 30 μm; in group G, the groove width was 5, 10, 20, and 30 μm, and the ridge width was 5 μm. The effect of microgrooves on the morphology, proliferation, and expression of fibrous markers of stem cells was systematically investigated in vitro. Moreover, thicknesses of fibrous capsules were evaluated after chips were implanted into the muscular pouches of rats for 5 months. The results show that microgrooves have almost no effect on cell proliferation but significantly modulate the morphology of cells and focal adhesions (FAs) in vitro, as well as fibrosis differentiation. In particular, the differentiation of stem cells is attenuated after the intracellular force caused by stress fibers and FAs is interfered by drugs, such as rotenone and blebbistatin. Histological analysis shows that patterns of high intracellular force can apparently stimulate soft tissue fibrosis in vivo. This study not only reveals the specific rules and mechanisms of ditch/ridge regulating stem cell behaviors but also offers insight into tailoring implant surface patterns to induce controlled soft tissue fibrosis.

Review of the Research on Soil Disturbance by Tools

The discrete element method can be used to analyze the interaction between tools and soil. It can be used to guide the optimal design of tools, but the appropriate simulation and test method selected is important to achieve the goal. This paper mainly introduces the disturbance of soil by tillage tools. The disturbance of the soil by tools include soil loosening, soil movement, and soil mixing. The disturbance contour is used to visually display the disturbance results, and the cross-sectional area, lateral soil throwing amount, ditch ridge height, ditch width, and ditch backfill are used to characterize the cross-sectional shape. Tracers are usually used to track soil particles to visually display the particle movement path during disturbance; this can be used to study the soil disturbance trend by the tools. When parameters and models are appropriate, the movement and contact of microscopic soil particles can be accurately simulated. By comparing the particle behavior of simulation and experiment, the contact model and contact parameters can be verified. The method introduced provides a reference for the optimal design of the tools and the research of disturbance by the tools.

Effect of damping ditch on blasting vibration reduction by field experiment and numerical simulation

In order to analyze the influence of a damping ditch on the blasting vibration, a large number of on-site monitoring tests with or without damping ditch were carried out based on the foundation pit excavation project. Based on the Sadovsky’s empirical formula, the optimized vibration velocity attenuation model was established by using the waveform subsection correspondence method and least square method. The calculation results are in good agreement with the measurement results. The average errors in radial direction and vertical direction are 17.04 % and 10.76 % respectively. A series of finite element models were established to study the influence of the damping ditch geometry on the damping effect. The experimental and numerical results show that the damping ditch can obviously reduce the blasting seismic effect, with the highest damping ratio in the area near blasting source. For different damping ditches, the damping ratio first increases and then decreases proportionally to the increase of distance between the measuring point and the blasting zone. The damping ditch depth has the best damping effect on blasting vibration, followed by the distance between the damping ditch and the blasting source, and finally the damping ditch width, which is consistent with the damping mechanism of theoretical analysis. The attenuation of the surface wave is only related to the damping ditch depth. The research results can provide a reference for the design of blasting vibration isolation.

Numerical investigation of the influence of banded sand ditches on water infiltration in fine-textured soil.

Enhancing rainwater infiltration is important to reduce the risk of urban waterlogging and improve the utilization rate of urban rainwater resources. Using the HYDRUS model, a mathematical model of soil water movement under a banded sand ditch pattern (the vertical excavation of a deep trench with heavy soil and filled with light soil) was created. Forty-six scenarios were designed to examine effects of sand ditch soil saturated hydraulic conductivity (Kss), original homogenous fine-textured soil saturated hydraulic conductivity (Kso), sand ditch width (W), spacing (S), and depth (D) on the soil infiltration rate (i). Results indicate that banded sand ditches cause increased permeation and have a significant turning point 't0' in the curve of 'i' for 't.' Taking 't0' as the boundary, 'i' can be divided into two stages (t ≤ t0 and t > t0), 'i' and 't,' for each stage according to the power function relationship; there is little change in power function indices, which can be fixed at 0.34 and 0.63, respectively. In addition, the coefficient has a linear relationship with Kss, Kso, W, S, and D. Thus, an estimation model of the soil infiltration rate under a banded sand ditch pattern was proposed and verified for reliability.

Effects of restoration and management of Mediterranean traditional water systems on Odonata alpha diversity: a long-term monitoring survey

The progressive abandonment and disappearance of traditional water uses and management of wetlands during the twentieth century has led not only to a loss of identity, heritage, and landscape values, but also to significant declines in the diversity and abundance of many organisms. Here, we take advantage of an existing project for the restoration and management of traditional irrigation infrastructures in the wetland of El Prado (Pinoso, south-eastern Spain) to evaluate the spatio-temporal effect of this action on the alpha diversity and abundance of Odonata. The wetland was organized in different sectors according to the coverage of riparian and aquatic vegetation, width and depth of watercourses, ditches and ponds, water flow, and restoration and management. Odonates were sampled every month for ten years. We used alpha diversity to measure biodiversity using Hill’s number diversity. To analyse how alpha diversity measures varied across all sectors sampled over the years, we determined diversity-time relationships. To assess the effects of the different variables on odonate biodiversity we used partial least squares regressions. Our results showed that restoration of traditional water infrastructures, encouraging the increase of aquatic vegetation cover, an adequate and regular management of riparian vegetation naturalizing the margins, as well as reducing speed of water flow have a positive effect on odonate diversity and abundance. Our study provides useful information for conservation and management of semi-arid wetlands and its associated water infrastructures by showing which actions are most successful to enhance biodiversity in one of the priority habitats for conservation in Europe.

Theoretical trafficability criterion and diagrammatic analysis based on rheological property of sea-floor sediment and topography

Trafficability criterion of a tracked miner is investigated when walking across deep-sea floor with obstacles by analyzing the mechanical property of deep-sea sediment and geometrical conditions of obstacles. Trafficability criterion can help predict and estimate the mining efficiency and working safety of the tracked miner on the deep-sea sediment. Deep-sea sediment has an obvious rheological property and its compression-sinkage-time relationship was adopted to describe the sinkage shape of track under different grounding pressure distributions. The area of the sinkage shape was classified and redefined according to the relationships with different traction forces based on work-energy theorem concept. A new trafficability criterion is then established based on the areas of sinkage shapes and the physical meaning of parameters in the criterion was explained diagrammatically in detail. As an application, a trafficable deep-sea ditch width and slope angle were calculated theoretically by combining the trafficability criterion and sinkage shapes analyses. The trafficability criterion is proved to be convenient and intuitive for quickly judging the trafficability problem of deep-sea tracked miner for common obstacles.

Technical Evaluation of Community Based Soil and Water Conservation Structures: A Case Study in Damot Gale Woreda, Wolayita Zone, South Ethiopia

In Arujya and Bilbo watershed, soil erosion is one of the series causes of soil degradation. The aim of this study was to technical evaluation of physical SWC measures constructed during the 2007 E.C campaign on cultivated field and implementation approaches in SWC development campaign and to analyze land use and land cover change. The data were collected through field measurements and satellite image download from NASA website. The selected physical soil and water conservation measures in both watersheds were level soil bund and level fanyajuu. For fanyajuu technical evaluation of the structures showed that generally in Bilbo watershed ditch depth, ditch width and spacing at 10-15% slope class and in Arujya watersheds ditch width and bottom width of embankment were lower than the recommended one and spacing at 15-30% slope higher than recommended. For soil bund, the technical evaluation ditch depth was in both watershed and ditch width in Bilbo was smaller than recommended and spacing in both watersheds wider than recommended value. In Bilbo watershed, forest coverage increased by 11.22% from 1987 to 2010. Grass land coverage decreased by 4.76% between 1987 and 2010 and then increased from 2010 to 2015. In Arujya watershed forest coverage was decreased by 0.46% from 1987 to 2010. Shrub and bush land cover decreased by 0.41% between 1987 and 2010. Cultivated land increased by 3.4% between 2010 and 2015. Similarly, forest land decreased by 0.13% in 2010. In the same period, the rate of shrubs and bushes decreased by 2.58% from 2015 to 2010. Technical evaluation needs some improvement in the design, community participation in planning phase and land cover changes shows affected cultivated land and vegetation cover through the population increment. It recommended that the future development activities will be used these technologies more for better management of the natural resources in watershed.

HAZARD ASSESSMENT OF SLOPE FAILURES IN CONGLOMERET AT TIKRIT, NORTHERN IRAQ

The degree and nature of slope failure hazards reflected the rock properties of unstable slopes, effective characteristics as slope high, slope angle, rock discontinuities, weathering, presence of water, and the consequence level depend on several parameters. Ditch (width, shape, volume), traffic, shoulder width to decide slopes mode and rest rock properties. Applying the Missouri Rock Fall Hazard Rating System Failure types happened and probably in the research area (Rock Fall, Toppling, Rolling). Nature parameters control hazard cases, station 7 represented alone the Tikrit bridge, water contact along a year, western shoulder of the bridge near the cliff, traffic problems, man-made, and buildings above slope apex, stations 4 and 5 people using Al-Bilaj area for swimming, fishery, and tourism, stations 1, 2, 3 and 6. Human activities are less than at stations 4 and 5. Consequently, the study area is sufferings hazard, and so should include warning suddenly failures. Stations1, 6 and 7 were classified as High-Risk High Consequence, while 2, 3, 4 and 5 were classified as High-Risk Low Consequence

Effect of the Size and Position of a Damping Ditch on the Reduction of the Blasting Vibration

The size and position of the damping ditch have a direct impact on the blasting vibration. In order to explore the effect of damping ditches of different sizes and positions, we investigated field blasting in the A3 area of the second phase of the Lufeng Nuclear Power Plant project. The simulation software ANSYS/LS‐DYNA was used to simulate the vibration propagation of damping ditches with different depths, widths, and positions. Secondly, the vibration data of the corresponding measuring points were collected and the amplitude reduction was analyzed in different situations. An analysis of the numerical simulation results showed that an increase in the damping ditch width increased the vibration amplitude at the top of the building. The depth and position of the damping ditch were the main factors affecting the damping performance. A regression analysis was conducted using the Sadove equation for vibration velocity. It was found that the regression coefficient of the Sadove equation did not meet the required standards when a damping ditch was present. The vibration attenuation equations were fitted for the top and the base of the building. The results of this study provide reference data for the excavation and arrangement of damping ditches in practical applications.

Analytical Investigation of Load Over Pipe Covered with Geosynthetic-Reinforced Sandy Soil

A geosynthetic reinforcement layer can be placed above the pipe in a ditch within the sandy soil cover to reduce the load on the crown of the pipe. The vertical load (V) on the crown of the rigid pipe without the geosynthetic layer is given as $$V={C_{\text{d}}}\gamma {B^2}$$, where $$\gamma$$ is the total unit weight of sandy soil, B is the ditch width and $${C_{\text{d}}}$$ is the load coefficient. The analytical formulation for load on the crown of the pipe covered with a single layer of geosynthetic-reinforced sandy soil has been developed earlier. In this paper, an attempt is made to derive an analytical formulation to investigate the load coefficient for pipe covered with sandy soil reinforced with two layers of geosynthetic reinforcement. It is observed that the two layers of geosynthetic reinforcement provide more benefits than a single-layer reinforcement in terms of the load reduction on the pipe. It is also noted that the stiffness of geosynthetic, buried depth, layer spacing and rut depth affect the load on the crown of the pipe. An illustrative example is presented in order to explain how the engineers can determine the load on the pipe using the analytical expression presented in this paper.

Reducing comminution over-grinding of powder coatings with modified grinding pins in an air classifier mill

Air classifier mill (ACM) is widely used in powder coating and mineral comminution process. One of the problems typically presenting in ACM is over-grinding, which leads to high energy consumption and broad particle size distribution (PSD). To decrease the excessive amount of fine particles in the products, 6 configurations of grinding pins with ditches in the impact surface were used in the experiments. The width and depth of ditches varied from 1.35 mm and 1 mm to 4.75 mm and 3 mm, respectively, while the interior angles in the ditches are the same. The particle size and PSD show that the ditches on the grinding pins have significant effect on the D10 values and the particle size span. The deepest and widest ditches (P4) result in largest D10 and smallest span in this study. The D10s of products ground by P4 increase by 24.1% for fine powder (D50 = 25 μm) and 16.0% for coarse powder (D50 = 33 μm), while the span decreases by 6.9% (D50 = 25 μm) and 6.4% (D50 = 33 μm) compared to regular cylindrical pins (PC), respectively. Meanwhile, it is found that the P4 configuration improves the energy utilization efficiency by 7.6% (D50 = 25 μm) and 3.4% (D50 = 33 μm), compared to that of the original PC pins.

Energy‐absorption performance of composite corrugated plates with corrugated‐shape ditch plug initiator

To improve the energy‐absorbing capacity of composite corrugated plate, the axial impact responses under axial quasi‐static crush loading is numerically studied and compared. Both the intra‐ply damage and delamination interface damage are considered. To accurately capture the progressive damage propagation, the failure material is modeled with a stiffness degradation method combined with the exponential damage evolution laws. To improve the crush performance, a novel corrugated‐shape ditch plug initiator (CDP) is proposed. The effects of extensive parameters including the ditch width and the inner geometry are carried out. Results show that well agreements between the numerical model and experimental results are identified on failure modes and energy‐absorption characteristics. The corrugated plate with CDP can increase the specific energy absorption by 20.3% than non‐plug initiator. The total of energy absorption is the decreasing function with respect to the width of ditch. The crushing performance can be improved due to the change in the inner geometry parameters. POLYM. COMPOS., 40:1708–1717, 2019. © 2018 Society of Plastics Engineers

Hazard assessment in rockfall-prone Himalayan slopes along National Highway-58, India: rating and simulation

A massive disaster occurred in June 2013 in Kedarnath, India, due to cloudburst and extremely heavy rain along the Chorabari glacier. The resulting flash floods further aggravated the instability of natural and hill cut slopes at different places on the downstream side. The village Rambara that existed in close proximity of Kedarnath was swept away under flow of debris and water. The immediate surrounding area, which housed over a hundred and fifty shops and hotels, was completely washed away leaving no trace of civilization. This calamity in Uttarakhand is considered as India’s worst natural disasters after the tsunami in December 2004. On the downstream of the affected areas lie other pilgrim destinations that witness innumerable footfalls every year. Investigation of the health of the slopes on the routes to these destinations is therefore very important to ensure minimal damage to humans and machinery. The Himalayan terrain is a tectonically active mountain belt, having a large number of unstable natural and road cut slopes. Such slopes with rugged topography lie in the high seismic vulnerability zone. Further, the instability is aggravated by natural and anthropogenic activities increasing at a rapid and uncontrollable rate. In the light of the Kedarnath tragedy, more advanced research is being conducted along the National Highways to monitor and prevent slope/structure failures. This study was conducted to evaluate the hazard potential along National Highway-58, near Saknidhar village of Devprayag district by analysing rockfall using hazard rating systems and numerical simulation. Rockfall hazard rating systems were applied to evaluate the conditions of the slopes and to identify the associated risks. Based on the field and laboratory analyses, the parameters required for numerical models were determined. The bounce height, roll-out distance, kinetic energy and speed of the detached blocks were determined by using a competent rockfall simulator. The results obtained were used to identify rockfall risk in the region. Optimization strategies were applied during investigation by modifying the slope angle, ditch width and ditch angle to assess the possibility of a hazard to occur in different scenarios. The simulation studies revealed that an increasing slope angle could significantly increase the kinetic energy of the rock blocks. However, an increase in the ditch angle and the ditch width reduces the energy of moving blocks. The maximum bounce height above the slope varied from 0.003 m to 0.8 m for 10-kg blocks, whereas the maximum velocity and the maximum kinetic energy under such circumstances were 7.882 m/s and 379.89 J, respectively. The barrier capacity was found to be 233.18 J for 10-kg falling blocks at a height of 10.02 m. From the optimization studies, it was found that the risk can be reduced by up to 13 % if the slope of 70° has a ditch angle of 15° while on a flat ditch, the maximum risk will be at an angle of 65°. If the ditch angle is increased, the vertical component of the falling blocks is more effective than that in case of a flat ditch. These optimization studies lay foundation for advanced research for mitigation of rockfall hazards in similar potential areas.

Factors affecting abundance and species composition of generalist predators (Tetragnatha spiders) in agricultural ditches adjacent to rice paddy fields

Agricultural ditches adjacent to paddy fields are expected to provide an alternative habitat to the fields for Tetragnatha spiders, a major component of the natural enemies of crop pests in rice paddy ecosystems. To better understand the spatial distribution of these spiders in agroecosystems, it is essential to evaluate their abundance and species composition in such alternative habitats. Here, we examined the factors determining abundance and species composition of Tetragnatha spiders in agricultural ditches around rice paddy fields. Field surveys were conducted in transects set along 43 concrete ditches in the northern Kanto region, Japan, prior to the rice growing season when spiders are absent in paddy fields. Four species of Tetragnatha spiders were found, with two species (T. maxillosa and T. extensa) accounting for 95% of the total abundance. These two species showed different responses to local and landscape factors. The abundance of T. maxillosa increased with ditch width, whereas that of T. extensa was highest at intermediate width. Vegetation height had a positive effect on the abundance of T. maxillosa but a negative one on that of T. extensa. Distance to the nearest forest had no effect on T. extensa, but negatively influenced T. maxillosa, indicating that forest environments are beneficial to the latter. Reflecting these differences, the proportions of the two species in overall Tetragnatha abundance varied depending on vegetation height and distance to forest. Our findings indicate that the potential for immigration of Tetragnatha spiders from ditches to fields depends on local conditions and the positional relationship to forest.

A liquid aluminum alloy electromagnetic transport process for high pressure die casting

For the electromagnetic transport (EMT) of liquid aluminum alloy during high pressure die casting (HPDC) by the plane induction electromagnetic pump (EMP), how to improve EMT efficiency and control EMT stationarity are key problems. Magnetic-flow coupling analysis was used to reveal effects of structural design and transport process parameters on EMT efficiency and stationarity. The output pump height of plane induction EMP was optimized by matching of iron core width W, coil width W′ and pump ditch width b, i.e., b values of bopt corresponding to 90% of the maximum output pump height, bopt/W=1.27 and bopt/W′=1. Both EMT efficiency and stationarity are achieved under the optimum transport current 32A. With the increase of the transport height from 350mm to 500mm, the EMT flow rate decreases from 4.28kg/s to 3.59kg/s, and the fillings of shot sleeve are always stationary. The transport tubes suffer a maximum positive pressure of 1.8×104Pa and a minimum negative pressure of −1.42×104Pa during EMT. For the liquid aluminum alloy soup occasions of 4.5kg, 6.5kg and 12.0kg, the transport time could be shortened significantly from manipulator’s 16s, 22s and 38s to EMT’s at most 2.195s, 2.75s and 4.28s, respectively. The developed EMT process with plane induction EMP for HPDC is a process with low cost, high transport efficiency and stationarity.

GS0534 湿式多板クラッチのドラグトルクに関する研究

When a multiplate wet clutch is idling, the drag torque occurs between disks. For the purpose of reduction in drag torque, the drag torque and visualization of a flow in the ditch of a clutch plate, were measured using the equipment which was modeled multiplate wet clutch in idling. The rotation speed and the ditch shape were changed. The rotation speed was 100,200,300rpm. The ditch shape was radial and slanting, and the ditch width was 1,2,4,8mm, respectively. As a result, the drag torque became lower in the case the ditch width was small, and the slanting shape. The velocity in a ditch will be one of the factors which have an influence on peripheral velocity and occur the drag torque fluctuate.