Flow Velocity Characteristics Research Articles

Regimes of thermo-compositional convection and related dynamos in rotating spherical shells

Convection and magnetic field generation in the Earth and planetary interiors are driven by both thermal and compositional gradients. In this work numerical simulations of finite-amplitude double-diffusive convection and dynamo action in rapidly rotating spherical shells full of incompressible two-component electrically-conducting fluid are reported. Four distinct regimes of rotating double-diffusive convection identified in a recent linear analysis (Silva, Mather and Simitev, Geophys. Astrophys. Fluid Dyn. 2019, 113, 377) are found to persist significantly beyond the onset of instability while their regime transitions remain abrupt. In the semi-convecting and the fingering regimes characteristic flow velocities are small compared to those in the thermally- and compositionally-dominated overturning regimes, while zonal flows remain weak in all regimes apart from the thermally-dominated one. Compositionally-dominated overturning convection exhibits significantly narrower azimuthal structures compared to all other regimes while differential rotation becomes the dominant flow component in the thermally-dominated case as driving is increased. Dynamo action occurs in all regimes apart from the regime of fingering convection. While dynamos persist in the semi-convective regime they are very much impaired by small flow intensities and very weak differential rotation in this regime which makes poloidal to toroidal field conversion problematic. The dynamos in the thermally-dominated regime include oscillating dipolar, quadrupolar and multipolar cases similar to the ones known from earlier parameter studies. Dynamos in the compositionally-dominated regime exhibit subdued temporal variation and remain predominantly dipolar due to weak zonal flow in this regime. These results significantly enhance our understanding of the primary drivers of planetary core flows and magnetic fields.

Study on Flow Velocity during Wheeled Capsule Hydraulic Transportation in a Horizontal Pipe

As a clean, low-carbon, and green hydraulic transportation technology, wheeled capsule pipeline hydraulic transportation is a transportation mode conducive to the sustainable development of the social economy. Based on the method of a physical model experiment and hydraulic theory, the flow velocity characteristics in the pipeline when the wheeled capsule with a length–diameter ratio of 2.5 and 2.14, respectively, was transported in the straight pipe section with an inner diameter of 100 mm were studied in this paper. The results show that in the process of transporting materials, the flow velocity distribution of the cross section near the upstream and downstream section of the capsule was basically the same, and the axial velocity was smaller in the middle of the pipe and larger near the inner wall of the pipe. The radial velocity distribution was more thinly spread near the pipe wall and denser near the center of the pipe. The circumferential flow velocity was distributed in the vicinity of the support body of the wheeled capsule. For any annular gap section around the wheeled capsule, the radial velocity of annular gap flow was very small, and the average radial velocity of annular gap flow was about 1/30 of the average axial velocity of annular gap flow and about 0.7 of the average circumferential velocity of annular gap flow. The axial, circumferential, and radial flow velocities on the same radius measuring ring changed with the polar axis in a wave pattern of alternating peaks and troughs. These results can provide the theoretical basis for optimizing structural parameters of the wheeled capsule.

Numerical Simulation of Flow Velocity Characteristics during Capsule Hydraulic Transportation in a Horizontal Pipe

Capsule hydraulic transportation is a kind of low-carbon and environmentally friendly pipeline transportation technique. In this study, the flow velocity characteristics in the pipeline when the capsule is transported in a straight pipe section were simulated by adopting the RNG (Renormalization Group) k–ε turbulence model based on Fluent software and experimentally verified. The results showed that the simulated value of flow velocity in the pipeline was basically consistent with the experimental value during transportation of the material by the capsule, and the maximum relative error was no more than 6.7%, proving that it is feasible to use Fluent software to simulate the flow velocity characteristics in the pipeline when the capsule is transported in a straight pipe section. In the process of material transportation, the flow velocity distribution of the cross-section near the upstream and downstream sections of the capsule was basically the same, which increased with the increased length–diameter ratio of the capsule. The axial flow velocity was smaller in the middle of the pipe and larger near the inner wall of the pipe. From the inner wall to the center of the pipe, the radial flow velocity first increased and then decreased. The circumferential flow velocity was distributed in the vicinity of the support body of the capsule. The axial flow velocity of the annular gap section around the capsule first increased and then decreased from the inner wall of the pipe to the outer wall of the capsule. In the process of transporting materials, the influence of the capsule on the flow of its downstream section was greater than that of its upstream section. These results could provide a theoretical basis for optimizing the technical parameters of capsule hydraulic transportation.

Аэрофотосьёмка водного пространства

During the development of water resources the characteristics of excitement, direction, and flow velocity, depth, points of bottom, temperature and chemical composition of water is to be taken into account. Some of these indicators are determined through the results of measuring single aerial photographs and their stereoscopic pairs. Making aerial photography (APS) of water surface on technology for topographic land survey enables obtaining only single overlapping aerial photographs, as the water surface is in constant motion. Stereoscopic pairs of aerial photographs can be obtained if photographing is performed simultaneously by two aerial cameras (AFA) with close elements of internal orientation. The author considers two technological schemes of using two AFA in aerial photography of water space

Prediction Method of Cavitation Jet Wave Attenuation Based on Five-Equation Two-Fluid Model

In this paper, the seven-equation two-fluid flow model is streamlined to a five-equation numerical calculation method. This method is applied to predict the wave attenuation of the cavitation jet. Compared with 9 different experimental schemes in two separate laboratories, it is found that the velocity flow characteristics are different from normal transient flow when the cavitation jet is formed in the pipeline. Such a difference in velocity flow characteristics will cause changes in the prediction deviation of pressure response time and amplitude. A numerical method for predicting the attenuation of pressure fluctuation with the cavitation jet is presented taken into account these flow characteristics. In this method, the unsteady friction model is opened after the jet wave transmits 3–5 cycles, and the cavitation jet wave attenuation is well simulated. This calculation method could provide a research basis for pipeline leakage, vibration, noise, and other fields that need accurate pressure signals.

Evaluation of ST2 as an early marker of heart failure with a preserved left ventricular ejection fraction in patients with persistent atrial fibrillation

Aim. To assess the diagnostic value of soluble ST2 (sST2) for early detection of heart failure with a preserved ejection fraction (HFpEF) in patients with persistent atrial fibrillation (AF).Material and methods. A total of 165 patients hospitalized with AF paroxysm were examined. The inclusion criteria were the persistent AF and LVEF >50% according to echocardiography. A cohort of 60 patients with persistent AF and preserved LVEF was formed. Patients were divided into 2 equal groups of 30 people depending on the HF presence, assessed on the basis of LV diastolic dysfunction with or without left atrial enlargement >34 ml/m2 or left ventricular mass index >110 g/m2 in men and 95 g/m2 in women, as well as an increase in the N-terminal prohormone of brain natriuretic peptide (NT-proBNP) >125 pg/ml. LVEF was calculated using the Simpson method; assessment of LV diastolic function was carried out with determination of transmitral flow velocity characteristics and visualization of mitral annulus motion. The NT-proBNP concentration was determined in blood serum using the Biomedica Group reagent (Austria), sST2 — using Presage ST2 (Critical Diagnostics, USA) by enzyme-linked immunosorbent assay on an Immulite 1000 analyzer (DPC, USA).Results. In patients with HFpEF and persistent AF, the correlation analysis showed a direct strong relationship between NT-proBNP and sST2 (r=0,726; p<0,05). To assess sST2 as a diagnostic criterion for HF, ROC curve was constructed. It was shown that with sST2 ≥16 ng/ml (AUC=0,89), the sensitivity of the method was 80%, the specificity — 83%.Conclusion. In patients with a persistent AF, serum sST2 concentration ≥16 ng/ml can be used as an alternative to the NT-proBNP criterion for early diagnosis of HFpEF.

DBD Plasma Combined with Different Foam Metal Electrodes for CO2 Decomposition: Experimental Results and DFT Validations.

In the last few years, due to the large amount of greenhouse gas emissions causing environmental issue like global warming, methods for the full consumption and utilization of greenhouse gases such as carbon dioxide (CO2) have attracted great attention. In this study, a packed-bed dielectric barrier discharge (DBD) coaxial reactor has been developed and applied to split CO2 into industrial fuel carbon monoxide (CO). Different packing materials (foam Fe, Al, and Ti) were placed into the discharge gap of the DBD reactor, and then CO2 conversion was investigated. The effects of power, flow velocity, and other discharge characteristics of CO2 conversion were studied to understand the influence of the filling catalysts on CO2 splitting. Experimental results showed that the filling of foam metals in the reactor caused changes in discharge characteristics and discharge patterns, from the original filamentary discharge to the current filamentary discharge as well as surface discharge. Compared with the maximum CO2 conversion of 21.15% and energy efficiency of 3.92% in the reaction tube without the foam metal materials, a maximum CO2 decomposition rate of 44.84%, 44.02%, and 46.61% and energy efficiency of 6.86%, 6.19%, and 8.85% were obtained in the reaction tubes packed with foam Fe, Al, and Ti, respectively. The CO2 conversion rate for reaction tubes filled with the foam metal materials was clearly enhanced compared to the non-packed tubes. It could be seen that the foam Ti had the best CO2 decomposition rate among the three foam metals. Furthermore, we used density functional theory to further verify the experimental results. The results indicated that CO2 adsorption had a lower activation energy barrier on the foam Ti surface. The theoretical calculation was consistent with the experimental results, which better explain the mechanism of CO2 decomposition.

New method to calculate the dynamic factor\u2013flow velocity in Geomorphologic instantaneous unit hydrograph

The determination of characteristic flow velocity is a hydrodynamic problem needs to be solved in the application of geomorphologic instantaneous unit hydrograph (GIUH) for runoff simulation in areas with no or limited data. In this study, 120 watersheds are collected to construct a regression model; 85 of these basins are used for regression analysis, and the 35 remaining basins are utilized to verify the feasibility of the constructed model. Random forest algorithm is applied to screen out important geomorphologic factors from the 16 extracted factors that may affect flow velocity. Multivariate regression is used to establish the numerical relationship between velocity and the selected factors. Sensitivity analysis of each adopted factor in the constructed model is conducted using the LH-OAT method. The rationality and feasibility of the regression model are validated by comparing the flow velocity calculation with a previous approach, which is also calculated based on geomorphological parameters. Subsequently, the runoff simulation based on the GIUH model is evaluated using the proposed technique. Results demonstrate that the proposed formula possesses high fitting accuracy and can be easily used to calculate flow velocity and generate GIUH.

Effects of acupuncture on carotid intima-media thickness and cerebral blood flow velocity in patients with mild-to-moderate hypertension

To observe the characteristics of carotid intima-media thickness (IMT) and cerebral blood flow velocity in patients with mild-to-moderate hypertension, and to evaluate the effects of acupuncture on carotid IMT and blood flow velocity of middle cerebral artery and vertebral-basilar artery. A total of 240 patients with mild-to-moderate hypertension who met the inclusion criteria were treated with Huoxue Sanfeng acupuncture method proposed by academician SHI Xue-min. The acupoints of Renying (ST 9), Quchi (LI 11), Hegu (LI 4), Zusanli (ST 36) and Taichong (LR 3) were selected. The treatment was given once a day, five times a week for 3 months. The carotid ultrasonography and transcranial color Doppler were performed before treatment and 3 months after treatment to evaluate the improvements of carotid IMT and brain blood flow velocity. Among 175 patients, 94.3% suffered from impaired carotid IMT. After acupuncture intervention, 7.7%-10.9% patients had improved IMT but 4.6%-6.3% had aggravated carotid IMT. There was no significant difference of carotid IMT before and after treatment (P>0.05). About 50% patients had abnormal intracranial blood flow velocity; after acupuncture intervention, 27.4%-33.3% patients who had the abnormal blood flow velocity had normal one, but 27.0%-52.5% patients who had normal blood flow velocity had abnormal one. After acupuncture intervention, the low-speed blood flow of MCA, VA and BA in female patients aged 41-60 years and the low-speed blood flow of MCA and VA in female patients aged 61-70 years were significantly improved (all P<0.05); the high-speed blood flow of MCA and VA in male patients aged 61-70 years and the high-speed blood flow of VA and BA in female patients aged 41-60 years were significantly decreased (all P<0.05). Nearly 95% of patients with mild-to-moderate hypertension had carotid IMT, and about 50% had abnormal blood flow velocity of intracranial artery. The present study failed to found significant effects of acupuncture on carotid IMT, but it shows acupuncture can generally improve the low blood flow velocity in women with mild-to-moderate hypertension.

Study on the influence of reflecting channel position on flow velocity characteristics of ultrasonic heat meter

In this paper, LES (Large eddy simulation) method is used to study the influence of different channel positions on the flow velocity of the ultrasonic heat meter, and the variation of the average linear velocity of different channel with time is researched. Through the calculation results, the velocity characteristics of 11 channels of the U-shaped reflecting device ultrasonic heat meter are analysed. The results show that the vortex behind the reflecting cylinder affects the velocity distribution in the channel. Statistical analysis shows that the linear average velocity in different positions of the channel fluctuates with time, but the fluctuation amplitude is basically the same. The average linear velocity asymmetry of reflecting channel far from the vortex zone is smaller, and the deviation of the average velocity is less than that of the average velocity, therefore, the distribution of the velocity is more reasonable.

Turbulent convective length scale in planetary cores.

Convection is a fundamental physical process in the fluid cores of planets. It is the primary transport mechanism for heat and chemical species and the primary energy source for planetary magnetic fields. Key properties of convection-such as the characteristic flow velocity and length scale-are poorly quantified in planetary cores owing to the strong dependence of these properties on planetary rotation, buoyancy driving and magnetic fields, all of which are difficult to model using realistic conditions. In the absence of strong magnetic fields, the convective flows of the core are expected to be in a regime of rapidly rotating turbulence1, which remains largely unexplored. Here we use a combination of non-magnetic numerical models designed to explore this regime to show that the convective length scale becomes independent of the viscosity when realistic parameter values are approached and is entirely determined by the flow velocity and the planetary rotation. The velocity decreases very rapidly at smaller scales, so this turbulent convective length scale is a lower limit for the energy-carrying length scales in the flow. Using this approach, we can model realistically the dynamics of small non-magnetic cores such as the Moon. Although modelling the conditions of larger planetary cores remains out of reach, the fact that the turbulent convective length scale is independent of the viscosity allows a reliable extrapolation to these objects. For the Earth's core conditions, we find that the turbulent convective length scale in the absence of magnetic fields would be about 30 kilometres, which is orders of magnitude larger than the ten-metre viscous length scale. The need to resolve the numerically inaccessible viscous scale could therefore be relaxed in future more realistic geodynamo simulations, at least in weakly magnetized regions.

Analysis of internal flow and outlet velocity characteristics associated with dust suppression nozzles and their impact on spray field

In order to understand the relationship between nozzle structure and spray field, the present paper conducts velocity-based parametric study on two types of dust suppression nozzles, focusing on the link among nozzle structure, velocity distribution, and the resulting spray field. The simulation investigation indicates that the increase of flow velocity mainly occurs in the convergence section and the outlet region of a nozzle, with its magnitude dictated by the convergence angle, ratio of inlet to outlet diameter, and the length–diameter ratio of the outlet. Based on the velocity distribution characteristic of axis direction and radial direction near different nozzles’ outlet, one can predict that fluid density is higher in the central axis region and lower in the boundary region in spray field with cylindrical outlet, which can form a “solid cone” shape and stable spray. In the case where the nozzle outlet has “dash” type, one can find that the spray field, which associated with this type of nozzle, is a fan-shaped, with the fluid density fluctuating up and down. The above hypothesis has been corroborated by the spray experiments which have been conducted here. The simulation results concerning the internal flow field in dust suppression nozzles can provide guidance over the nozzle design and the parametric optimization and are of great significance to enhance the atomization quality of spray field.

Modeling Hydro-Dynamics in a Harbor Area in the Daishan Island, China

This study presents an incorporation and application of a two-dimensional, unstructured-grid hydrodynamic model with a suspended sediment transport module in Daishan, China. The model is verified with field measurement data from 2017: water level, flow velocities and suspended sediment concentration (SSC). In the application on the Daishan, the performance of the hydrodynamic model has been satisfactorily validated against observed variations of available measurement stations. Coupled with the hydrodynamic model, a sediment transport model has been developed and tested. The simulations agreed quantitatively with the observations. The validated model was applied to the construction of breakwaters and docks under a different plan. The model can calculate the flow field and siltation situation under different breakwater settings. After we have analyzed the impact of existing breakwater layout schemes and sediment transport, a reasonable plan will be selected. The results show that the sea area near the north of Yanwo Shan and Dongken Shan has a large flow velocity exceeding 2.0 m/s and the flow velocity within the isobath of 5 m is small, within 0.6 m/s. According to the sediment calculation, the dock project is feasible. However, the designed width of the fairway should be increased to ensure the navigation safety of the ship according to variation characteristics of cross flow velocity in channel.

Anomalous transport of a passive scalar at the transition to dynamical chaos in a barotropic shear layer

Abstract In this paper we are concerned with the problem of anomalous transport in a quasi-two-dimensional (barotropic) shear layer localized in the horizontal channel with rigid walls and subjected to the beta-effect. The flow may be regarded as a model of a zonal shear layer in the Earth’s atmosphere and ocean as well as in laboratory experiments. External (bottom) friction is taken into account by adding Rayleigh damping to two-dimensional equations. The attention is focused on a new mechanism of anomalous wave transport, when the disturbances producing stochastic layers in the vicinity of a vortex chain are caused by the transition to dynamical chaos. The problem is solved numerically using a pseudospectral method. The supercriticality is defined as the ratio of the characteristic flow velocity to the critical one. The critical wavenumber of the linear eigenvalue problem is such that 7 vortices are excited on a flow period, while the transition to chaos begins when 5 vortices are excited. The anomalous transport is examined at the first stage of the chaos onset, when the frequency spectra of spatial harmonics are quite narrow, thereby the trajectories of tracer particles are formed like in the kinematic model. The self-similarity property of variance in the ensemble of tracers is confirmed and the exponents of time power law are obtained. The Poincare map is drawn and the average displacements of the tracers are computed.

Coupled DEM-LBM simulation of saturated flow velocity characteristics in column leaching

Heap leaching is a process extensively used by the mining industry to recover valuable metals from low-grade ores. However, the flow of the solution in a heap leaching system is disordered, uncontrollable and difficult to predict. To investigate the velocity characteristics of saturated flows in column leaching under different conditions, a combined experimental and numerical approach was carried out in the current work. MRI (magnetic resonance imaging) technology was employed in the column leaching experiment and numerical simulations were performed by combining the discrete element method (DEM) with the lattice Boltzmann method (LBM) to predict the microscopic seepage velocity field in the leaching column. The fluid flow and solid particles were modelled by the LBM and DEM respectively, and the interfacial interaction between the fluid and the solids was resolved by the immersed boundary method (IMB). It was demonstrated that the maximum fluid velocity is positively correlated with irrigation rate and porosity. Moreover, the preferential flow mainly passes through the main seepage channel. Thus, the numerical model developed in the present work is a reliable prediction tool for understanding the regularities of mesoscopic seepage velocity distributions in column leaching processes.

Hydrodynamic Pressure and Velocity Distributions in the Interlayer Crack of Ballastless Track under High-Speed Train Load: A Theoretical Analysis

In the abundant rain or poor drainage areas, there will be serious water damage existing in the interlayer of ballastless track. The essence of water damage of ballastless track is a dynamic development process of damage shape under the combined action of train load, hydrodynamic pressure, and flow velocity. In view of the distribution characteristics of hydrodynamic pressure and flow velocity in the interlayer crack of ballastless track under the high-speed train load, the simplified mechanics model for water and composite slab with interfacial crack is proposed in accordance with the water damage characteristics of ballastless track. Based on the conservation of mass and momentum theorem, the analytical expressions of water pressure and velocity in the saturated water crack were deduced. Similarly, the analytical expressions of water pressure and velocity in the unsaturated water crack were deduced by adding the state equation of ideal air. Considering that the water does not flow back timely, the analytical expressions of water pressure and velocity in another kind of unsaturated water crack were deduced. The results show that the hydrodynamic pressure and flow velocity in the interlayer crack are synthetically determined by multiple influencing factors such as fluid viscosity, load characteristic, crack shape, absolute pressure at the crack mouth, and initial volume of the air in the crack, and there is an intersecting phenomenon between influencing factors. When there is a small amount of air at the crack tip, the pressure and velocity distribution in the crack can be divided into three parts in terms of air-water interface and stagnation point. When the crack is filled with water, the hydrodynamic pressure tends to decrease along the direction of the crack mouth, and the distribution along the whole crack approximates to a cubic polynomial curve. Similarly, the flow velocity increases along the direction of crack mouth, and the distribution along the whole crack approximates to a quadratic polynomial curve.

Effects of vegetation patch density on flow velocity characteristics in an open channel

The aquatic plants are often found in natural rivers, and they affect the channel flow structure significantly. To study the effects of the vegetation density a (the frontal area per volume) on the flow velocity characteristics, rigid bamboo circular cylinders are chosen as the model emergent vegetation. In the experiments, the density of the vegetation takes various values while all other flow parameters are kept constant. A 3-D acoustic Doppler velocimeter (ADV) is used to measure the local flow velocities for different vegetation densities. The results show that the existence of the vegetation patch leads to an increase of the depth-averaged velocity on the right and left sides behind the vegetation patch, and it increases monotonically with the vegetation density. For different vegetation densities, the lateral distribution of the stream-wise velocity behind the vegetation patch follows approximately an S-shaped profile when a ≤ 60 m-1, and a logarithmic profile if a > 60 m-1. The vertical distribution of the stream-wise velocity along the channel varies with the vegetation density and also follows an S-shaped distribution in a certain range, with the locations and the ranges being affected by the vegetation density.

Improved formulae of velocity distributions along the vertical and transverse directions in natural rivers with the sidewall effect

The distribution of flow velocity is a basis for the research into the transport of flow and sediment in natural rivers. Characteristics of velocity distribution in narrow-deep natural rivers are different from those in wide-shallow open channels, and the effect of sidewalls on the distribution of flow velocity is considerable, which leads to a large transverse gradient of the depth-averaged velocity, with the maximum velocity occurring below the water surface. Based on the Reynolds equation of turbulence flow and the analysis of the features of velocity distribution in natural rivers, improved formulae with two empirical parameters α and β have been proposed for the velocity distributions along the vertical and transverse directions, with the effect of sidewalls being considered, through solving the definite solution problem by the method of variable separation. The proposed formulae were validated fully through comparisons between the calculated and measured velocity profiles and depth-averaged velocities at several sections in the Yangtze and Baitarani Rivers, with close agreement between them being obtained. The formula of velocity distribution along the transverse direction in natural rivers with the sidewall effect was also compared with previous studies, and the calculation accuracy of this formula at a section with a narrow-deep geometry was higher than the accuracy of the previous equations. It is confirmed that the proposed formulae can reproduce well the distribution characteristics of flow velocity along the vertical and transverse directions in narrow-deep natural rivers, with a more wide application in practice.

Electric Field Effect on the Thermal Decomposition and Co-Combustion of Straw Pellets with Peat

The main goal of the present study is to obtain a more effective utilization of wheat straw for energy production during a co-combustion with peat. For this purpose, an electric field was applied to the flame produced by the combustion of volatiles. This work combines experimental study and mathematical modelling of the processes developing during the co-combustion of straw pellets with peat pellets. The main gasification/combustion characteristics, the heat output from the device and the composition of the flue gas were analysed by varying separately the bias voltage of the axial electrode and the straw mass load in the mixture with intention to assess the electric field impact. A mathematical model of the electric field impact on the main combustion characteristics (flow velocity, flame temperature and composition) of co-combustion have been built within the MATLAB environment. The numerical simulation was performed for two dominant second order combustion reactions of CO and H2 with account for the electric field effect on the displacement of equilibrium during the thermal decomposition of the biomass.

Assessment of dynamic impact force of debris flow in mountain torrent based on characteristics of debris flow

Landslides and debris flows that occur around residential areas are considered, globally, as significant disasters that cause damage to human life and property. With terrain slope defining the flow characteristics of debris flows, flow depth, flow velocity, and impact force vary by time and distance. In particular, when a structure is located in the flow path of debris flows, the flow characteristics of debris flows vary by terrain slope and direction angle. To simulate the flow characteristics of these debris flows, the simulation results obtained by FLO-2D were analyzed with six-stage conditions for the research area. In the analysis, the flow depth, flow velocity, and impact force were estimated on the basis of the outlet of the research area in the presence and absence of structure(s) at certain distances. With this, the variation of the impact force in accordance with the variation of the flow depth of the debris flows was highly similar to the simulation results obtained by FLO-2D, when the correction index (α) of the suggested dynamic impact force equation was 0.3–0.4. There were sections where the estimated value of the impact force was overestimated near the outlet, and it was judged that the fixed values of the terrain factors (width, roughness coefficient, slope, etc.) caused the impact force to be overestimated. However, the correlation analysis showed that the correlation index was above the normal ranges in the suggested dynamic impact force equation for debris flows with the application of the terrain factors.