Reynolds Stress Turbulence Model Research Articles

VLF oscillation mechanism analysis of underwater vehicle based on overlapping grid

ABSTRACT The present study aims to investigate the VLF oscillation mechanism of underwater vehicles motion by conducting numerical simulation on the AFF-1. The straight-line simulations of AFF-1 were performed using RANS equations with a Reynolds stress turbulence model at different speeds, and an initial flow field with converged resistance results was obtained. Meanwhile, the accuracy of the numerical model and input parameters were validated by the resistance results. The sinuous motion of AFF-1 was simulated based on dynamic fluid body interaction (DFBI) and overlapping grid. The results indicated that the inherent instability of the AFF-1 significantly impacts its motion dynamics. Specifically, when AFF-1was in straight-line motion at a constant forward velocity, it was subjected to the influence of pressure component of hydrodynamic force and moment, resulting in slow trajectory divergence motion of AFF-1. In scenarios where manual manipulation is employed, this instability leads to the emergence of VLF oscillations.

Effect of momentum flow ratio on entrainment of a confined coaxial jet in a co-flow

Iron ore pellet production processes produce large amounts of CO2 emissions when burning fossil fuels. One example is the grate-kiln process, where normally a coal flame is used to indurate pellets. To mitigate the emissions, coal used in rotary kilns can be replaced with for example hydrogen. However, the fuel is mixed with secondary process air, and replacing a solid fuel with a gaseous one changes the mixing characteristics. This demands different means of injecting the fuel. A coaxial jet can be used to control the mixing of fuel and secondary air, as well as the flow field. The aim is to control the mixing of hydrogen and secondary air to achieve a hydrogen flame that is similar to the reference coal flame. This study numerically investigates different coaxial jet configurations. Steady-state simulations of a simplified model of the real kiln are performed using a Reynolds Stress turbulence model. Results show that decreasing the momentum flow ratio between the outer and inner jet, M jet , to a certain value delays the spread of the hydrogen jet and thus gives a longer jet. Further decreasing this ratio gives an even longer jet, but has the side effect of producing recirculation of hydrogen.

Numerical analyses of water swirls in aquaculture tanks

Water swirls were observed in both model and prototype aquaculture tanks with bottom drains. This phenomenon was seldom replicated in studies of flow fields of water in aquaculture tanks with computational fluid dynamics. A commonality of these studies is that the linear eddy-viscosity turbulence models were employed. This study delves into the water swirls from the aspect of the generation of the turbulence kinetic energy; both the linear and nonlinear eddy-viscosity turbulence models are used, as well as a Reynolds stress turbulence model. A novel identification method is utilized to pinpoint vortex structures. Numerical results affirm the outstanding performance of the Reynolds stress model to estimate the flow fields of water in aquaculture tanks. Both the linear and nonlinear eddy-viscosity models overestimate the kinetic turbulence energy in the stagnation zone of swirls. The overestimation can be restrained by including the effect of the streamline curvature correction (SCC) to the turbulence production term. Even so, the SCC does not help to improve the estimating accuracy between the Reynolds stress tensor and the mean rate-of-strain tensor. While the nonlinear model offers some improvements, the Reynolds stress model provides a more effectvie solution. After that, we calculate the flow fields of water in aquaculture tanks with different inlet–outlet configurations with the Reynolds stress turbulence model. Both the vertical and horizontal scales of water swirls increase with inlet velocities and Froude numbers, where the Froude number is based on the bottom draining velocity and the water depth above the bottom drain. The vertical distributions of the water residence time in aquaculture tanks are shown to improve the design of tanks.

Design and Analysis of Gas Cyclone with Arc-Shaped Cone Using Bézier Curve for Improved Performance

Abstract The research investigates novel gas cyclone separators with curved conical sections, comparing eight configurations with varying curvature sizes. Gas cyclones are traditionally used as particle separators to remove dust from gas streams, aiming to achieve a dust-free gas flow at the exit pipe while recovering particles to the dust outlet. Computational fluid dynamics (CFD) was employed to model the gas cyclone using the Reynolds stress turbulence model (RSM); the study examines flow fields and pressure losses. It finds that increased curvature correlates with reduced pressure drop. The curved profile is derived from the Bézier curve, characterized by a set of control points determining its shape. This study examines eight cyclone configurations with the intermediate point placed at varying fractions of the main radius: 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, and the main radius itself. The investigation focuses on the impact of different conical segment shapes on cyclone performance, highlighting how convex variants outperform others at higher flow rates while concave variants exhibit higher pressure drop. The pressure drop in the convex variant with an intermediate point position equal to the main radius decreased by 50%. These findings suggest the potential of the convex variant in certain operating conditions over traditional designs with improved particle capture efficiency.

Study on the deposition characteristics of fine particles at local components in air conditioning ventilation ducts

Air conditioning ventilation ducts are widely used in contemporary buildings. The change of airflow direction in the ducts local components can easily lead to the deposition of particles, which can easily form a secondary source of indoor air pollution and have an adverse effect on human health. Based on this, this paper utilizes the existing experimental data to validate the numerical simulation. The Reynolds stress turbulence model combined with the method of enhanced wall function was used to investigate the deposition characteristics of fine particles in different local components. For the first time, local deposition rates and deposition hotspots were proposed to analyze the simulation results. The results show that the local deposition rate of the particles with a particle size of 1μm do not differ much on each wall surface, and the particles are deposited more uniformly on each wall at the local components, with a difference of less than 10 %, and the maximum local deposition rate is on the outer wall of the local components. When the particle size is larger than 10μm, the local deposition rate on the outer wall of the local component increases significantly, with a maximum increase of 23.3 % (compared to 5μm particles), and the maximum local deposition rate increases slowly with increasing air velocity, with a maximum increase of less than 8 %. The effect of increasing particle size on the maximum local deposition rate is much greater than the increase in air velocity. With the increase of air velocity and particle size, the deposition hotspots of both the 90° bend and the T-type tee duct migrate to the middle of the wall, and the deposition hotspots of the 4-way duct migrate to the inside of the wall.

Numerical simulation of involute-plate research reactor flow behavior using RANS, LES and DNS

This paper investigates the flow behavior of involute-plate research reactors by performing Reynolds-Averaged Navier Stokes simulation (RANS), Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) of the channel flow between fuel plates. By modeling turbulence with different numerical approaches, this study provides data with three levels of fidelity. For the RANS simulation, three widely used turbulence models, i.e., k-ε, k-ω, Reynolds Stress Turbulence model (RST) are applied by using the commercial CFD code STAR-CCM + . For LES and DNS, the open-source CFD code, Nek5000, is used given its outstanding scalability on High Performance Computer (HPC) and high-order technique. The results from RANS simulations are compared with that from LES and DNS for benchmarking. Both macroscale parameters and turbulence statistics, such as velocity magnitude, lateral velocity and turbulence kinetic energy, are presented and analyzed.The results from RANS simulation achieve good agreement with LES and DNS on velocity and turbulence kinetic energy prediction. The RST turbulence model predicts the most similar flow pattern of lateral velocity as compared to LES and DNS. The Lambda-2 (λ2) criterion with a reasonable threshold is used to demonstrate the instantaneous vortices distribution in the involute channel from both LES and DNS calculation. The DNS simulation captures more detailed turbulence especially near the corner, which explains the discrepancy between LES and DNS results near the corner. The normalized RMS error are defined and calculated to assess the performance of those turbulence models. The RST model captures the anisotropic feature of turbulence, which enable it to outperform other turbulence models for predicting the flow behavior in an involute channel. Although some discrepancies are found between LES and DNS results in the corner, the overall deviations between LES and DNS are found to be small. Given that the computational cost of DNS calculation is an order of magnitude higher, using LES data for benchmarking RANS model is a cost-effective approach.

Hydrodynamic characteristics analysis of series hydraulic cyclone separators for pond aquaculture wastewater purification

This study introduces a series of hydraulic cyclone separators designed to efficiently remove sediments and other high-density particulate matter from pond aquaculture wastewater. A three-dimensional two-phase model of these hydraulic cyclone separators was developed using the discrete phase model (DPM) and Reynolds stress turbulence model (RSM) based on numerical simulation theory. The computational fluid dynamics (CFD) method was validated by comparing it with experimental data, and an analysis of the hydrodynamic characteristics of the hydraulic cyclone separators was conducted. Furthermore, the relationships between structural parameters and separation efficiency were examined using Pearson's correlation coefficient. The findings reveal that the length of the first-stage cyclone column significantly influences the tangential velocity distribution within the second-stage cyclone, while the length of the second-stage cyclone column predominantly affects the pressure distribution of the first-stage cyclone. Increasing the column length enhances the overall particulate separation efficiency of the system. Moreover, adjustments in the split ratio of the first-stage cyclone have a notable impact on the tangential velocity and pressure distribution within the second-stage cyclone. Increasing the split ratio proves beneficial in improving the separation efficiency of particulate matter. This study provides valuable insights into the design and optimization of hydraulic cyclone separators, offering a dependable computational model for predicting and understanding their flow behavior and separation performance effectively.

Ship Flow of the Ryuko-maru Calculated by the Reynolds Stress Model Using the Roughness Function at the Full Scale

The k-omega SST turbulence model is extensively employed in Reynolds-averaged Navier–Stokes (RANS)-based Computational Fluid Dynamics (CFD) calculations. However, the accuracy of the estimation of viscous resistance and companion flow distribution for full-sized vessels is not sufficient. This study conducted a computational analysis of the flow around the Ryuko-maru at model-scale and full-scale Reynolds numbers utilizing the Reynolds stress turbulence model (RSM). The obtained Reynolds stress distribution from the model-scale computation was compared against experimental measurements to assess the capability of the RSM. Furthermore, full-scale computations were performed, incorporating the influence of hull surface roughness, with the resulting wake distributions juxtaposed with the actual ship measurements. The full-scale calculation employed the sand-grain roughness function, and an optimal roughness length scale was determined by aligning the computed wake distribution with Ryuko-maru’s measured data. The results of this study will allow for the direct performance estimation of full-scale ships and contribute to the design technology of performance.

CFD Simulation of an Industrial Dust Cyclone Separator: A Comparison with Empirical Models: The Influence of the Inlet Velocity and the Particle Size on Performance Factors in Situation of High Concentration of Particles

The present work is dedicated to the study of multiphase turbulent and three-dimensional rotational flow in dust cyclones, a contribution to air pollution control. Cyclones are widely used devices for the separation of constituents from solid-gas mixtures in industry. In order to improve the filtration efficiency of cyclones, and to reduce the pressure drop, parametric numerical simulation studies using the Fluent code have been conducted to characterise the effects of the parameters affecting the operation of these devices through their performance indicators. In this work, the effect of inlet velocity and the particle size on the turbulent flow air in the cyclone is presented. Numerical simulation of the flow by Fluent code using three numerical models: the first based on the dissipation of kinetic energy by viscosity (RNG) K-epsilon and standard K-epsilon as well as the last based on the solution of Reynolds stress equations (RSM), combined with the multiphase mixing model, gave interesting results in terms of the pressure and flow field in the separator, the variation of inlet velocity, and the variation of particle size. Validation with experimental and empirical results showed the advantage of the Reynolds stress turbulence model (RSM) over the standard K-epsilon and RNG K-epsilon. The RSM model better captures physical phenomena in an intense vortex flow in the presence of walls. But it is characterised by a very long calculation time and requires large machine resources. An alternative to this model is RNG K-epsilon model, which offers a reasonable calculation time with acceptable results (maximum deviation of 5 %) for speed values below 10 m/s. In the absence of numerical resources, certain empirical models such as those of First (for the evaluation of pressure drop) and Iozia and Leith (for evaluation of efficiency) may well be useful for the dimensioning of the cyclone.

Surface Currents Effect in the Explicit Algebraic Reynolds Stress Turbulence Model for Simulation of Lateral Buoyant Jets in Cross-Flow

Surface Currents Effect in the Explicit Algebraic Reynolds Stress Turbulence Model for Simulation of Lateral Buoyant Jets in Cross-Flow

Numerical simulation of gas-solid flow in a cyclone separator with additional inlet

In this study, an additional inlet was added to the gas-solid cyclone separator to enhance the separation efficiency. Four different heights were tested, including 0.95D, 1.4D, 1.5D, and 1.95D (D is the diameter of the cylindrical section). The investigation involved two inlet flow conditions: increasing and dividing the inlet flow rate. The finite volume method and Reynolds stress turbulence model were used to solve the averaged Navier–Stokes equations, whereas the Eulerian–Lagrangian approach and discrete phase model (DPM) were applied to track particles with a uniform diameter of 0.5–1.8 microns as the discrete phase. Owing to the low Stokes number and small and low-volume-fraction particles, a one-way coupling method was employed between air and the particles. The addition of an additional inlet reduced the static pressure in the center and downstream areas and increased the reverse flow velocity at the end of the cyclone. The installation of an additional inlet at 0.95D had the most positive effect on the separation efficiency, with an increase of 28.8% in the increasing flow rate case and 19.6% in the dividing flow rate case compared with the cyclone without an additional inlet. Furthermore, the increase in the separation efficiency of the submicron particles was greater than that of the larger particles in both flow distribution cases.

Numerical simulation of landscape ecological river flow structure based on vegetation patch distribution and fragmentation.

The self-organizing biological characteristics of vegetation and human activities lead to the disruption of the continuous spatial attributes of natural watersheds, which are significant factors affecting river wetland ecosystems. To clarify the landscape ecological flow characteristics of vegetation patch distribution and fragmentation, this study used the three-dimensional Reynolds stress turbulence model in ANSYS Fluent software. The model considered three vegetation patch coverages under two different submersion states and four fragmentation types of vegetation patches under the same coverage conditions within specific vegetation areas. The flow characteristics of longitudinally discontinuous rigid vegetation patches, occupying half of the width of the river channel, were numerically simulated. The model's applicability was verified by indoor open-channel flume experiments. The results indicated that: (1) The streamwise velocity in vegetated areas is significantly lower than in non-vegetated areas, and the difference in flow capacity between vegetated and non-vegetated areas increases with patch coverage and fragmentation degree. (2) In the non-submerged state, the maximum Reynolds stress in the vegetated area is located at the bottom of the vegetation and is negatively correlated with patch coverage but positively correlated with fragmentation degree. In the submerged state, the maximum Reynolds stress is located near the top of the canopy and is positively correlated with both patch coverage and fragmentation degree. (3) The longitudinal turbulent kinetic energy in the vegetated area is significantly higher than in the non-vegetated area. In the non-submerged state, the turbulent kinetic energy in the vegetated area is negatively correlated with patch coverage but positively correlated with fragmentation degree. In the submerged state, the turbulent kinetic energy of the longitudinal distribution in the free layer of the vegetated area is positively correlated with patch coverage, negatively correlated with fragmentation degree, and is only reflected in the upstream vegetation area.

The effects of inlet number and positions on the flow pattern and performance of a Stairmand cyclone

This study conducts numerical investigations to analyze the influence of inlet number and vertical positioning on flow patterns, collection efficiency, pressure drop, and efficiency of Stairmand cyclones. The maximum displacement of inlets is considered approximately equal to the cyclone diameter, and the inlets are arranged in a gradual manner. The Reynolds Stress Turbulence model (RSM) was employed to calculate flow properties in turbulent conditions. Out of the 44 cases examined, the four-inlet cyclone with L4=0.1 exhibited the smallest cut-size diameter, while the single-inlet cyclone with L1=0.9 displayed the lowest pressure drop. Notably, shifting one of the inlets of the two-inlet cyclone by 20% relative to the cyclone diameter resulted in higher pressure levels on the cyclone wall compared to other geometries explored in this study. Collection efficiency in cyclones is generally enhanced by an increase in tangential velocity, but it is also influenced by the position of the inlet(s).

Numerical investigation of cooling performance of 3D-printable cooling structure for aero-engine combustor

Thermal protection is an essential technology for gas turbine hot components to cope with the unprecedented thermal loads, and to ensure their enduring and efficient operation. A 3D-printable hybrid cooling cellular structure is suggested in this paper, the cooling property of which in a Can-type combustion chamber with chemical reaction considered is evaluated in detail. Reynolds Stress Turbulence Model together with the non-premixed combustion model are used to resolve the detailed flow structures and turbulence-chemistry interactions. Cases of cooling cellular with various film hole inclined angles are compared and analyzed. Results show that the cooling cellular can reduce the temperature of combustor liner noticeably, especially at the region near the second row of dilution holes. Meanwhile, the cooling performance is improved as the decrease of inclined angle, with an improvement of 29.1% as the inclined angle range from 90° to 30°, because the smaller incline angle is more resilient to coolant lift-off. A comparation with effusion cooling scheme is also made and concluded that the case of hybrid cooling exhibits a 673%-1409% higher porosity ratio, while the cooling effectiveness is reduced about 3.6%-8.3%. The lower performance of the hybrid cooling is explored further with a flat plate conjugate heat transfer numerical test, and ultimately attributed to the relative lower flow rate of coolant air induced by higher pressure loss of hybrid cooling cellular. Finally, the compound angle is further introduced into the hybrid cooling cellular. Results show that the impact of compound angle on cooling property depends highly on the angle between the film outflow and the swirling main-flow. The performance of compound angle cases will only increase when cooling cellular deflects in opposite directions of swirling flow, not vice versa. Overall, the hybrid cooling cellular shows a great potential in the cooling design of combustor liner. A smaller incline angle with compound angle deflected in the opposite direction of the swirling main-flow are also recommended for increased cooling performance.

Sensitive analyses of flow property to turbulence model in swirls simulation within aquaculture tanks

Water swirls in tanks with bottom drain(s), which is observed in aquaculture tanks. Numerical simulation of the swirling field with the general two-equation turbulence models fails to describe the swirling phenomenon and the investigating results are less convincing. This study simulates the swirling flow fields with four categories of turbulence models, they are the laminar model, the turbulent-viscosity model, the Reynolds stress model, and the Large Eddy Simulation model. Results show that the swirling phenomenon is successfully numerically reproduced except for the turbulent-viscosity model. Although the flow properties predicted with the turbulent-viscosity model are different from other turbulence models, the results are meaningful from the perspective of statistical items (mean, standard variation, uniformity, PDF, CFD). For cases with swirls, the flow field can be divided into a forced vortex and a free vortex, and their tangential velocity profiles can be described with a theoretical formula. Considering the numerical cost and the reproduction of experiments, the Reynolds stress turbulence model is preferable in studies of the flow properties of aquaculture tanks.

Analysis of the effect of rigid vegetation patches on the hydraulics of an open channel flow with Realizable k-ε and Reynolds stress turbulence models

In this study, the effect of vegetation patches naturally located in the river and stream bed on flow characteristics was observed under laboratory conditions by using representative rigid vegetation. Then, the behavior of rigid vegetation was compared with two different (Realizable k-ε and Reynolds Stress) turbulence models using a CFD software (ANSYS-Fluent). Firstly, our use of models was validated. Then, they were used for numerical simulation. The velocity distributions energy dissipation, and turbulent intensities, at the determined points for the patches located in the downstream part, were analyzed with graphics and simulations. The vertical distribution of the average velocities was calculated at typical locations downstream. The magnitude of flow velocities was observed to decrease within the vegetation patch zone. The minimum values of the velocity magnitude were observed just behind the vegetation structures. Higher velocities were simulated in the vegetation patch regions compared with the gap regions. This identifies that the gap areas are appropriate for the deposition of sediments and advantageous for aquatic living beings in terms of physical atmosphere and nutriment. A maximum of 7 % energy dissipation difference occurred between the highest and lowest SVF values. For equal SVF values, a 1 % energy dissipation difference was obtained. This situation can be associated with the number of rods, and rod spacing being equal to the rod diameter. The 3-D turbulence intensity was only numerically measured and compared. Between the Realizable k-ε model and the RES model, the maximum 0.05 %turbulence density difference was observed (for SC1 and SC3 scenarios). We can associate this situation with the vortex and complex turbulent flow, which is formed from the channel bottom to the water surface, depending on the diameter of the rigid vegetation and the rod sequence. It was observed that there are effective methods to predict the flow model within both models.

Effect of a curved turning vane on the heat transfer and fluid flow of four-pass internal cooling channels of gas turbine blades

This numerical study examined the effects of a curved turning vane on the heat transfer and pressure loss of a four-pass internal cooling channel. Three-dimensional omega-based Reynolds stress (RSM-ω) turbulence model equations were used in the computation process. Three different curved turning vane configurations were studied using a simple, without a turning vane under stationary and rotating conditions for Reynolds numbers between 20,000 and 60,000 and a rotation number of 0.042. The numerical results showed good agreement with previous experimental data. Under both stationary and rotating conditions, the curved turning vane in a hub turn reduced the pressure drop significantly compared to the conventional turning vanes. Although a curved turning vane attenuated overall heat transfer, the local heat transfer increased it in particular regions, such as the hub turn and the fourth turn of cooling passages, particularly in cases with smaller radii. Coolant flow through the hub turn of the serpentine channel can reduce recirculation, separation, and flow impingement, which are unfavorable factors of pressure loss, owing to the semi-circular configuration of the curved turning vane. Regarding the rotating conditions, four-pass channels with a smaller radius of a curved turning vane provide better overall cooling performance.

Dynamic Stall Control for a Vertical-Axis Wind Turbine Using Plasma Actuators

Dynamic stall is a major challenge for vertical-axis wind turbines (VAWTs) as it negatively impacts the aerodynamic performance of VAWTs, resulting in a reduction in net power output from the turbines. This study explores the use of alternating current dielectric barrier discharge plasma actuators for controlling dynamic stall on a VAWT. The flow control process is resolved using a two-dimensional unsteady Reynolds-averaged Navier–Stokes equations simulation with a Reynolds stress turbulence model adopted. The macro-effect of the plasma discharge on mean flow is modeled by an empirical body force model. The detailed flow actuation procedure is simulated. Numerical results show that the flow control process is dominated by the spanwise vortices, which result from the interaction between the plasma discharge and separated flow. The spanwise vortices not only prevent the development of a leading-edge separation bubble into a dynamic stall vortex, but also suppress the flow separation at the trailing edge. The application of plasma forcing has been found to greatly enhance the aerodynamic performance of the turbine in terms of the moment coefficient and averaged power coefficient of the turbine blades. Furthermore, we examine how the positioning of the plasma actuators and the freestream wind velocity affect flow control. The optimal actuation location is determined, and the plasma actuators are seen to be able to substantially enhance the net power output of the blades at all freestream speeds.

Realizability-preserving time-stepping for the differential Reynolds stress turbulence models

In the context of incompressible turbulence modelling, differential Reynolds stress models allow a better representation of turbulence anisotropy than classical linear eddy viscosity models and are less expensive than large eddy simulations in terms of computational cost. They rely on a modelled transport equation for the Reynolds stress tensor, which is by definition a covariance tensor and must remain symmetric positive semi-definite. However, the solution of the modelled and discretized transport equation may not preserve these mathematical properties. In the present article, a methodology to time-split Reynolds stress R__ terms in the transport equation is proposed using a decomposition theorem which proves the realizability of R__ provided realizable initial conditions. Realizability-preserving time-steppings are designed for several differential Reynolds stress models. The numerical schemes are presented in a finite volume context but may be used with others space discretization schemes. The realizability, precision and robustness of the numerical scheme is verified through the anisotropy time evolution in homogeneous shear-flow simulations with various initial conditions.

Оцінка впливу канавок у дифузорі на втрати повного тиску

The subject of the study is the total pressure in the diffuser channel with passive control of the boundary layer. The object of this research is a diffuser channel with riblets. The mechanism of total pressure reduction due to the presence of longitudinal grooves on the streamlined surface is related to the strengthening of viscous forces acting in the transverse direction caused by them. These forces generate a relatively calm flow inside the riblets, which pushes out the turbulent flow, which causes surface friction, pushing it away from the surface. Thus, the process of generation and growth of elongated wall turbulent formations. In addition, in the presence of riblets, a change in the pressure field in the transverse direction is possible, as well as the creation of a quasi-two-dimensional flow in the immediate vicinity of the wall. In this work, the aim of research to investigate the influence of riblets on total pressure loss in the diffuser channel with the purpose of evaluating the influence of riblets on the change in the nature of the flow and the change in pressure, using numerical modeling. To study the nature of the flow in the diffuser channel, we resolved the following tasks: a diffuser channel was modeled with the following dimensions: length L=50 mm, hydraulic diameter at the inlet X=25 mm, hydraulic diameter at the outlet Y=40 mm, riblets diameter d=4 mm, number of riblets n =4 and n=8. The study was compared with a diffuser with the following dimensions: length L=50 mm, diameter at the inlet X=25 mm, diameter at the outlet Y=40 mm. To research the flow in the diffuser, the method of numerical experiment was chosen. An unstructured calculation grid was used in the diffuser for the research. The calculation of the turbulent gas flow was performed by numerically solving the averaged Navier-Stokes equations. During the numerical simulation of the flow, the Reynolds stress turbulent viscosity model will be used. As a result, using a diffuser with riblets increases the coefficient of hydraulic resistance compared to a smooth diffuser. The resistance reduction mechanism does not work due to the relatively short length of the diffuser and small longitudinal vortices of the riblets scale do not have time to form. There are pressure increasing instead of laminization of the flow and pressure decreasing. Scientific novelty - received new data on the effect of riblets in the diffuser channel on the total pressure loss coefficient. Practical significance - the obtained results can be used to control the boundary layer in diffuser channels (in diffuser compressor grates) to improve their characteristics.