Turbulence Integral Scale Research Articles

Prediction of along-wind loading on tall building based on two-dimensional aerodynamic admittance

The mismatch of simulated turbulence integral scale may occur in some wind tunnel model tests, especially in a short wind tunnel, which would lead to inaccurate prediction of the wind loading based on traditional aerodynamic admittance (traditional AAF) containing the three-dimensional effect (3D-effect). For this, a method for prediction of along-wind loading on tall building based on two-dimensional aerodynamic admittance (2D-AAF) is introduced. The key to the method is to identify the 2D-AAF which does not contain the 3D-effect through separating the 3D-effect from the traditional AAF. With this method, the 2D-AAFs of the along-wind loading of a CAARC building model in two turbulent flow fields with different turbulence integral scales are identified. As expected, the traditional AAF which contains 3D-effect changes with the turbulent flow field because 3D-effect is related to the turbulence integral scale. Different from the traditional AAF, the 2D-AAFs obtained in two different turbulent flow fields are almost consistent, confirming that the 2D-AAF is independent of the turbulence integral scale. An empirical expression for the 2D- AAF of along-wind loading of CAARC building is then proposed by fitting the experimental data. A comparison between the high-frequency-force-balance (HFFB) measurements conducted in a simulated boundary layer flow field and the prediction values shows that the reproduced spectrum of along-wind loading based on the 2D-AAF has high accuracy, verifying the validity of proposed prediction method.

Strategies for identifying the two-dimensional aerodynamic admittance functions of a bridge deck

Pressure measurement experiments were carried out on three streamlined box girders with three geometric ratios of 1:50, 1:75 and 1:100 in five turbulent flow fields generated by grids. The turbulence intensities only affected the root-mean-square (RMS) of the pressure coefficients in the flow separation zone, while the turbulence integral scales affected the RMS of the pressure coefficients over the entire cross-sections. The spanwise correlations of the fluctuating winds and buffeting forces mainly varied with the turbulence integral scales. New strategies are proposed to identify the two-dimensional aerodynamic admittance functions (2D AAFs) using the two-wavenumber approach. The two-wavenumber coherence functions of fluctuating winds or buffeting forces obtained through new strategies do not need to use the empirical spanwise root-coherence function models compared to the traditional strategy. A complete analysis of 2D AAFs based on different strategies was performed. The determined 2D AAF using spanwise root-coherence function models varied with the kinds of spanwise root-coherence function model and relied on spacings chosen to fit, which caused the 2D AAF to vary in size. Therefore, the strategy without any spanwise root-coherence function models is recommended, and it is confirmed to give reliable and repeatable bridge deck 2D AAFs.

Identification of modal parameters of long-span bridges under various wind velocities

The modal parameters identification of bridges under non-stationary environmental excitation has caught the attention of researchers. This paper studies the non-stationarity of wind velocity, and extracts the time-varying mean wind velocity based on a discrete wavelet transform and recursive quantitative analysis. The calculated turbulence intensity and turbulence integral scale under the non-stationary model are smaller than those under the stationary model, especially the turbulence integral scale. The empirical wavelet transform is used to identify the modal parameters of long-span bridges, and the power spectral density spectrum is proposed as a replacement for the Fourier spectrum as the basis of the frequency band selection. The bridge modal parameters are then compared using the covariance-driven stochastic subspace system identification method (SSI-COV) and the Hilbert transform method based on an improved empirical wavelet transform (EWT-HT). Both methods can accurately identify the modal frequency, and the absolute difference between these two methods is equal to 0.003 Hz. The wind velocity results in a change of less than 1% in the modal frequency. The absolute difference between the modal damping ratios identified using SSI-COV and EWT-HT is significant and can reach 0.587%. The modal damping ratios are positively correlated with the mean wind velocities, which aligns with the quasi-steady assumption. In addition, the applicability of SSI-COV and EWT-HT is also evaluated using the standard deviation, coefficient of variation, and range dispersion indicators. The results show that the EWT-HT is more applicable to the identification of the modal parameters of long-span bridges under non-stationary wind velocities.

A methodology to initialize tumble flow fields for fast 3D-CFD simulations of pent-roof SI engines

The demand of powertrain technologies able to efficiently employ several non-fossil fuels types, as bio or synthetic ones, compels to develop simplified strategies to accelerate the engines industrial optimization. High-tumble ultra-lean SI engines are currently an attractive option, thanks to their fuel flexibility and the potential of extending the lean combustion limit with novel ignition strategies. This work presents a methodology to initialize tumble flow fields at closed-valves inside pent-roof SI engines, without the need of simulating the gas exchange process. First, assuming an elliptical-shaped vortex, a velocity field is initialized into the cylinder according to the target tumble ratio at inlet valve closing (IVC). Then, the flow field is evolved at fixed piston position for a time duration proportional to the integral time scale of turbulence. This process is essential to adapt the vortex morphology to the surrounding geometrical details, despite some kinetic energy is lost due to frictions. To compensate this last effect, the velocity field is re-scaled at the end of the process to match the initial tumble ratio. Finally, the parameters affecting the tumble initialization are calibrated by comparing the development of the flow-field during the compression stroke with the results from a full-cycle simulation in a pent-roof SI engine. The methodology is validated on the Darmstadt optical engine. First, the numerical velocity fields are compared against PIV measurements at different crank-angles. Then, the combustion prediction is also evaluated, to assess the quality of the initialized tumble flow field. The achieved results are satisfactory, demonstrating the industrial applicability of the presented methodology.

Variation Characteristics of the Wind Field in a Typical Thunderstorm Event in Beijing

The understanding of wind field characteristics during thunderstorms is key to structural design for resistance to thunderstorms. In this paper, the directional thunderstorm wind model is adopted to analyze the characteristics of vertical variations of the wind field in a typical thunderstorm event in the Beijing urban area, based on the measured data. First, the longitudinal and lateral fluctuating wind speed components were decoupled and the change of direction was obtained. Then, variation of the wind speed, wind direction, turbulence intensity, turbulence integral length scale, and gust factor with the height and time were studied. The measured thunderstorm wind spectrum and the coherence function of horizontal longitudinal reduced turbulent fluctuations were analyzed and compared with empirical models. The results showed that the wind speed profile presented an obvious “nose shape” near the peak wind speed. The longitudinal turbulence integral scale was larger than the lateral one. The Von Karman spectrum is relatively effective in fitting the thunderstorm wind spectrum. Compared with synoptic winds, the gust factor during the pass of thunderstorm wind is larger, so it seems necessary to consider the influence of thunderstorm wind in engineering design.

Energy- and flux-budget theory for surface layers in atmospheric convective turbulence

The energy- and flux-budget (EFB) theory developed previously for atmospheric stably stratified turbulence is extended to the surface layer in atmospheric convective turbulence. This theory is based on budget equations for turbulent energies and fluxes in the Boussinesq approximation. In the lower part of the surface layer in the atmospheric convective boundary layer, the rate of turbulence production of the turbulent kinetic energy (TKE) caused by the surface shear is much larger than that caused by the buoyancy, which results in three-dimensional turbulence of very complex nature. In the upper part of the surface layer, the rate of turbulence production of TKE due to the shear is much smaller than that caused by the buoyancy, which causes unusual strongly anisotropic buoyancy-driven turbulence. Considering the applications of the obtained results to the atmospheric convective boundary-layer turbulence, the theoretical relationships potentially useful in modeling applications have been derived. The developed EFB theory allows us to obtain a smooth transition between a stably stratified turbulence to a convective turbulence. The EFB theory for the surface layer in a convective turbulence provides an analytical expression for the entire surface layer including the transition range between the lower and upper parts of the surface layer, and it allows us to determine the vertical profiles for all turbulent characteristics, including TKE, the intensity of turbulent potential temperature fluctuations, the vertical turbulent fluxes of momentum and buoyancy (proportional to potential temperature), the integral turbulence scale, the turbulence anisotropy, the turbulent Prandtl number, and the flux Richardson number.

Effects of the Turbulence Integral Scale on the Non-Gaussian Properties and Extreme Wind Loads of Surface Pressure on a CAARC Model

Effects of the Turbulence Integral Scale on the Non-Gaussian Properties and Extreme Wind Loads of Surface Pressure on a CAARC Model

Large-scale circulations in a shear-free convective turbulence: Mean-field simulations

It has been previously shown [Elperin et al., “Formation of large-scale semi-organized structures in turbulent convection,” Phys. Rev. E 66, 066305 (2002)] that a non-rotating turbulent convection with nonuniform large-scale flows contributes to the turbulent heat flux. As a result, the turbulent heat flux depends explicitly not only on the gradients of the large-scale temperature, but also on the gradients of the large-scale velocity. This is because the nonuniform large-scale flows produce anisotropic velocity fluctuations, which modify the turbulent heat flux. This effect causes an excitation of a convective-wind instability and formation of large-scale semi-organized coherent structures (large-scale convective cells). In the present study, we perform mean-field numerical simulations of shear-free convection, which take into account the modification of the turbulent heat flux by nonuniform large-scale flows. We use periodic boundary conditions in horizontal direction as well as stress-free or no-slip boundary conditions in vertical direction. We show that the redistribution of the turbulent heat flux by the nonuniform large-scale motions in turbulent convection plays a crucial role in the formation of the large-scale semi-organized coherent structures. In particular, this effect results in a strong reduction of the critical effective Rayleigh number (based on the eddy viscosity and turbulent temperature diffusivity) required for the formation of the large-scale convective cells. We demonstrate that the convective-wind instability is excited when the scale separation ratio between the height of the convective layer and the integral turbulence scale is large. The level of the mean kinetic energy at saturation increases with the scale separation ratio. We also show that inside the large-scale convective cells, there are local regions with the positive vertical gradient of the potential temperature, which implies that these regions are stably stratified.

The probabilistic turbulence profiles of tropical cyclones in open and flat terrain

The fluctuating winds are usually characterized in the frequency domain by the power spectral density (PSD) function and the coherence function, in which the turbulence intensity and turbulence integral scale are key parameters to describe the gust characteristics of turbulent winds. These parameters estimated from tropical cyclone (TC) observations show significant scattering. Starting from a critical review of the state of the art, the Von Karman spectra are chosen for the TC winds. The turbulence intensity and the turbulence integral scale used in wind spectral functions are discussed in detail. By introducing randomness into the empirical models, the probabilistic longitudinal turbulence profiles of TCs are derived from a wide collection of field measurements with open and flat terrain in the literature. Moreover, the probabilistic models of the lateral and vertical turbulence components are obtained by assuming proportionality between these two components and the longitudinal one. The mean and standard deviation of the developed models for TCs are compared with those defined in the seven major wind loading codes worldwide as well as the model given by Solari to testify these models and illustrate their differences to synoptic winds.

Режимы взрывного горения при аварийных взрывах газовых облаков в открытом пространстве

Emergency explosions of steam clouds in the open space occur in the deflagration combustion mode. Destructive force of the explosive waves is mainly determined by the rate of combustion in the steam cloud. Therefore, the issue of explosive combustion rate is the key one for predicting explosion parameters. To form the waves of destructive force, it is required that the combustion rate of the substance in the cloud increase by 30 or more times compared to laminar. The main and generally recognized mechanism of combustion intensification is turbulization of the process as a result of interaction of the gas flow field with various obstacles located in the area of the exploding cloud. In the work, the analysis focuses on the combustion processes in the obstacles with continuously changing blocking of space. Under such conditions, the combustion is not structured, it smoothly changes its characteristics, and not jerks at the locations of blocking barriers. That is, explosive combustion can be considered as a classic turbulent combustion of a homogeneous mixed mixture. The work gives preference to the analysis of works, in which the turbulent combustion rate is presented as allowing a change in the scale of turbulence. The results of these works are presented in the form of functions ff(U¢/Sl, l/d) of the ratio of the pulsation component of turbulence to the laminar combustion rate, and the ratio of the integral scale of turbulence to the thickness of the laminar flame. The work gives a comparison of the turbulent combustion velocity depending on the U¢/SL ratio for three values l/d = 100, 1000, 10 000. On the basis of the turbulent combustion modes diagram, the zones of applicability of various methods for determining the turbulent combustion rate are shown. The paper expresses preference for the Peters theory as the most universal and giving a realistic value of the turbulent combustion rate at l/d >> 1.

Experimental Study of the Fluctuating Wind Characteristics of Typhoon Jangmi Measured at the Top of a Building

Based on wind field data measured during the landfall of Typhoon Jangmi in Wenzhou in 2008, this study analyzes wind field characteristics, including wind speed, wind direction, probability density, turbulence intensity, gust factor, peak factor, power spectrum, turbulence integral scale, coherence, and the autocorrelation coefficient of Typhoon Jangmi. Results showed that the wind field characteristics for the east and west measuring points were basically the same and followed an approximately similar pattern. The probability density of fluctuating wind tends to obey a Gaussian distribution. The turbulence intensity gradually decreases with increasing 10 min averaged wind speed, but the reduction rate gradually drops. The turbulence intensity is affected by the change in a time interval because turbulence intensity decreases as the time interval increases. With an increase in the 10 min average wind speed and time interval, the gust factor decreases. The peak factor decreases, though insignificantly, with increasing mean wind speed, and the distribution of peak factors is greatly scattered. The variation in the peak factor with time is in good agreement with the Durst curve. The gust factor increases as the turbulence intensity increases and is in line with the empirical curves of Ishizaki, Choi, and Cao. The power spectra of the fluctuating wind speed of Typhoon Jangmi in all directions agree well with Von Karman’s empirical spectrum. The turbulence integral scale increases slightly with increasing average wind speed, and the distribution is relatively scattered. The coherence of the fluctuating wind speed components matches the exponential function proposed by Davenport, and the autocorrelation coefficient decreases as τ increases.

A physics-based model for wind turbine wake expansion in the atmospheric boundary layer

Analytical wind turbine wake models are widely used to predict the wake velocity deficit. In these models, the wake growth rate is a key parameter specified mainly with empirical formulations. In this study, a new physics-based model is proposed and validated to predict the wake expansion downstream of a turbine based on the incoming ambient turbulence and turbine operating conditions. The new model utilises Taylor diffusion theory, the Gaussian wake model, turbulent mixing layer theory and the analogy between wind turbine wake expansion and scalar diffusion. These components ensure that the model conserves mass and momentum in the far wake and accounts for the ambient turbulence and turbine-induced turbulence effects on the wake expansion. To account for the turbulence relevant scales that contribute to the wake expansion, the model uses the root-mean-square of the low-pass filtered radial velocity component. A simplified version that only requires the unfiltered velocity standard deviation and turbulence integral scale is also proposed. In addition, a new relation for the near-wake length is derived. The model performance is validated using large-eddy simulation data of a wind turbine wake under neutral atmospheric conditions with a wide range of incoming turbulence levels. The results show that the proposed model yields reasonable predictions of the wake width, maximum velocity deficit and near-wake length. In the case with a relatively low incoming streamwise turbulence intensity of 0.05, the ambient and turbine-induced terms in the model contribute almost equally to the wake width, rendering them both crucial for reasonable wake predictions.

Evaluation of effect of micro-vortex generator on dynamic characteristics of unsteady partial cavitating flow over hydrofoil

The unsteady characteristics of cavitation induce a series of destructive effects, such as cavitation erosion, vibration, and noise. Passive control of hydrofoil cavitation involves changing the structure or material of the hydrofoil surface, thereby inhibiting cavitation damage, and vortex generators (VGs) are the most popular means of passive control because of their effectiveness, simplicity, and lower production and installation costs. In this study, a new VG structure that can improve the cavitating flow state of a hydrofoil is proposed. A multiphase volume-of-fluid model is used to capture the interface between different phases, the Schnerr–Sauer model is used to describe the cavitation process, and turbulence is modeled by large-eddy simulation. The evolution characteristics of the cavitating flow field around a National Advisory Committee for Aeronautics (NACA) 0015 hydrofoil are investigated numerically both with and without the VG to illustrate its control effect. It is found that the VG can change the hydrodynamic characteristics of the cavitating flow field around the hydrofoil, such as the cavity morphology, the vortex structures, and the peak and power spectral density of the pressure. Upon using Lagrangian coherent structures, the motion state of the fluid particles and the distance between adjacent fluid particles are found to change dramatically with time under the effect of the VG. Upon using dynamic mode decomposition, the VG is found to decrease the energy in the first three modes, whereas that in mode 4 is larger without the VG, thereby suggesting that the VG might help to reduce flow noise. Finally, it is found that the VG converts laminar flow to turbulence, thereby increasing the turbulence intensity of the wake flow field and decreasing the maximum value of the turbulence integral scale.

Analysis of Turbulence Parameters of Typhoon Morakot along the Southeast Coast of China

The southeast coastal region of China is frequently affected by typhoons. The observation station was chosen to be located on the roof of Wenzhou University’s architectural engineering building to collect real-time wind speed data during the landfalling of Typhoon Morakot to investigate the properties of the near-ground wind field of typhoons. The turbulence characteristics of the near-ground wind and its variation with time intervals are analyzed on the basis of real-time measured data. The results show that the turbulence intensity only changes with the mean wind speed under relatively low wind speeds. The gust factors exhibit a scattered distribution under low wind speeds and tend to cluster together when the wind speed exceeds 8 m/s. With increasing time intervals, the turbulence intensity and the gust factor gradually decrease. The relationship between turbulence intensity and gust factor is obtained by the measured data and then compared with the empirical formulas. The peak factor remains constant while the mean wind speed changes, but diminish as the time intervals rise. The turbulence integral scale of typhoons slightly increases with the increasing mean wind speed, and its value falls between 70 and 150.

Conditional simulation of 3D nonstationary wind field for sea-crossing bridges

This paper presents a framework for the conditional simulation of a 3D nonstationary wind field for super-long sea-crossing bridges based on wind speed time histories measured by limited anemometers on site. The variations of wind characteristics along the bridge deck with multi-elements are considered in this framework. The wind characteristics, including mean wind speeds, mean wind directions, turbulence intensities, turbulence integral scales, evolutionary wind spectra and spectral parameters, coherence functions and function parameters, at the measurement points are first obtained by analyzing the measured wind speed time histories. The wind characteristics are then extended over all the simulation points along the deck of the sea-crossing bridge using the spatial interpolation method and considering the variation of deck height above the sea level using the profiles of mean wind speeds, turbulence intensities and turbulence integral scales estimated from the measured wind speed time histories. After working out wind cross correlation functions, wind speed time histories at all simulation points over the sea-crossing bridge can be conditionally simulated. The proposed framework is finally applied to a real 22.9 km sea-crossing bridge under Typhoon Higos. The conditionally simulated wind speed time histories at all simulation points of the bridge are acceptable and consist a complete wind field which can be used for the buffeting analysis of the bridge.

Experimental study of turbulent thermal diffusion of particles in inhomogeneous and anisotropic turbulence

We experimentally studied the turbulent thermal diffusion of small particles in inhomogeneous and anisotropic stably stratified turbulence produced by one oscillating grid in the air flow. The velocity fields have been measured using Particle Image Velocimetry (PIV). We have determined various turbulence characteristics: the mean and turbulent velocities, two-point correlation functions of the velocity field, and an integral scale of turbulence from the measured velocity fields. The temperature field has been measured with a temperature probe equipped with 12 E thermocouples. Spatial distributions of micrometer-sized particles have been determined by a PIV system using the effect of the Mie light scattering by particles in the flow. The experiments have demonstrated that particles are accumulated at the minimum of mean fluid temperature due to the phenomenon of turbulent thermal diffusion. Using measured spatial distributions of particles and temperature fields, we have determined the effective turbulent thermal diffusion coefficient of particles in inhomogeneous temperature-stratified turbulence. This experimental study has clearly detected the phenomenon of turbulent thermal diffusion in inhomogeneous turbulence.

Buffeting response evaluation of slender linear structures considering the influence of the aspect ratio on the scale effect

Scale effect has a non-negligible influence on the buffeting response of a slender linear structure. Among them, the effect of the ratio of the turbulence integral scale to the structure width is widely recognised. However, past research neglected the role of the aspect ratio, and the experiments did not accurately simulate the turbulence characteristics of the atmospheric boundary layer. This let to distortions in the prediction results of the structural buffeting response obtained based on wind tunnel tests. Based on the recent scholars' understanding of the effect of the aspect ratio on aerodynamic admittance and the concept of integrated transfer function, a method for predicting the buffeting response of slender linear structures based on the three-dimensional two-wavenumber buffeting analysis theory is proposed in this paper. A calculating example of a slender linear structure with an airfoil section is designed. The sectional model vibration test is used to investigate the effect of the two important influencing parameters of the scale effect, especially the aspect ratio, on the integrated transfer function and buffeting response. The prediction value of the actual structural buffeting response based on an integrated transfer function identified through the sectional model vibration test is compared with the theoretical calculation value, and it verifies the accuracy and effectiveness of the proposed method. Meanwhile, a problem existing in the test methods for identifying the required aerodynamic parameters in the theoretical calculation of the buffeting response of slender linear structures is identified, and an effective solution is provided.

Magneto-thermal instability in galaxy clusters – II. three-dimensional simulations

ABSTRACT In the intracluster medium (ICM) of galaxies, exchanges of heat across magnetic field lines are strongly suppressed. This anisotropic heat conduction, in the presence of a large-scale temperature gradient, destabilizes the outskirts of galaxy clusters via the magneto-thermal instability (MTI), which could drive observed ICM turbulence. In this paper we continue our investigation of the MTI with 3D simulations using the Boussinesq code snoopy. We redress two issues intrinsic to our previous 2D study: an inverse energy cascade and the impossibility of dynamo action. Contrary to 2D simulations, we find inconsequential transport of energy across scales (most energy is dissipated at the same scale as its injection) and that turbulent eddies are vertically elongated at or below the thermal conduction length yet relatively isotropic on larger scales. Similar to 2D, however, the saturated turbulent energy levels and the integral scale follow clear power-laws that depend on the thermal diffusivity, temperature gradient, and buoyancy frequency. We also show that the MTI amplifies magnetic fields, through a fluctuation dynamo, to equipartition strengths provided that the integral scale of MTI turbulence is larger than the viscous dissipation scale. Finally, we show that our scaling laws are consistent with extant observations of ICM turbulence if the thermal conductivity is reduced by a factor of ∼10 from its Spitzer value, and that the stable stratification significantly reduces the vertical elongation of MTI motions on global cluster scales.

Dynamo instabilities in plasmas with inhomogeneous chiral chemical potential

We study the dynamics of magnetic fields in chiral magnetohydrodynamics, which takes into account the effects of an additional electric current related to the chiral magnetic effect in high-energy plasmas. We perform direct numerical simulations, considering weak seed magnetic fields and inhomogeneities of the chiral chemical potential ${\ensuremath{\mu}}_{5}$ with a zero mean. We demonstrate that a small-scale chiral dynamo can occur in such plasmas if fluctuations of ${\ensuremath{\mu}}_{5}$ are correlated on length scales that are much larger than the scale on which the dynamo growth rate reaches its maximum. Magnetic fluctuations grow by many orders of magnitude due to the small-scale chiral dynamo instability. Once the nonlinear backreaction of the generated magnetic field on fluctuations of ${\ensuremath{\mu}}_{5}$ sets in, the ratio of these scales decreases and the dynamo saturates. When magnetic fluctuations grow sufficiently to drive turbulence via the Lorentz force before reaching maximum field strength, an additional mean-field dynamo phase is identified. The mean magnetic field grows on a scale that is larger than the integral scale of turbulence after the amplification of the fluctuating component saturates. The growth rate of the mean magnetic field is caused by a magnetic $\ensuremath{\alpha}$ effect that is proportional to the current helicity. With the onset of turbulence, the power spectrum of ${\ensuremath{\mu}}_{5}$ develops a universal ${k}^{\ensuremath{-}1}$ scaling independently of its initial shape, while the magnetic energy spectrum approaches a ${k}^{\ensuremath{-}3}$ scaling.

Investigations on Wind Characteristics for Typhoon and Monsoon Wind Speeds Based on Both Stationary and Non-Stationary Models

Stationary models are usually applied for wind characteristics analysis. However, nonstationarity has been found in the field measurements of typhoons in recent studies; therefore, using traditional models with stationary assumptions to conduct wind characteristics is inadequate. In this research, data acquisition of typhoon wind speeds and monsoon are conducted based on the wind field measurements. Wind speeds of typhoon “Maria” passing through Pintan, Fujian Province, China and the monsoon from 2017.10–2018.10 were obtained to investigate wind characteristics. The run test method is utilized to show that non-stationarity exists in both typhoon and monsoon wind speed, and the percent of non-stationary increases with the increase in time interval. Additionally, results show that stronger non-stationarity exists in typhoon wind speed compared with monsoons. Based on a self-adaptive procedure to extract time varying mean wind speed, a non-stationary model is established to compare with the non-stationary model, which has been applied in the traditional wind characteristic analysis. The fluctuating wind characteristics such as turbulence intensity, gust factor, turbulence integral scale, and wind speed spectrum are analyzed to compare the two models. Results show that the difference of such characteristics between the two models increases with the time interval, indicating the necessity of consideration of non-stationary models, especially for design specifications with larger time intervals. Influences of time intervals are investigated, and relevant recommendations are provided for wind resistance specifications. Our conclusions may provide reference for wind resistance design in engineering applications.