Fude Guo’s research while affiliated with Xi'an Jiaotong University and other places

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Publications (9)


Investigation of turbulent mixing layer flow in a vertical water channel by particle image velocimetry (PIV)
  • Article

December 2010

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116 Reads

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3 Citations

The Canadian Journal of Chemical Engineering

Fude Guo

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Ximin Zhang

Turbulent mixing layer flow in a vertical water channel was experimentally investigated by particle image velocimetry (PIV). The mixing layer is produced by a specially designed insert plate placed in the channel with a low- and high-speed side velocity ratio of 0.25. The Reynolds number based on the velocity difference of two streams and the spanwise vorticity thickness at the place where the mixing layer start merging ranges from 2184 to 14 672. The results show that there are large coherent vortex structures near the centreline of the mixing layer. Both instantaneous kinetic energy and spanwise vorticity always concentrate at the location where the coherent structures connect or meet each other. The normalised dimensionless Reynolds stresses and average spanwise vorticity show self-similar, respectively, under different Reynolds numbers at the same cross-section in the down streamwise direction. Every component of Reynolds stresses increases but the vorticity decreases with the downstream distance. For all Reynolds number, the peak values of mean vorticity in the streamwise direction appear the same decay speed. The splitter plane wake causes a negative peak of the mean vorticity where the mixing layer merges. The negative peak values of vorticity increase with the Reynolds number. The dimensionless negative peak values decrease exponentially with Reynolds number and reach a constant when the Reynolds number is large enough.


Investigation of Turbulent-Mixing-Layer Flow with Polymer Additives and Bubble Injection by Particle Image Velocimetry

September 2010

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11 Reads

Turbulent-mixing-layer flows in a vertical channel with polymer additives and bubble injection were experimentally studied by particle image velocimetry (PIV). The transparent test section was 1.0 m long with a 0.04 m × 0.11 m cross section, and the main stream was split into two substreams by a specially designed splitter. The velocities on the low- and high-speed sides are 0.36 m/s and 1.4 m/s, respectively. The Reynolds number based on the velocity difference between the two streams and the vorticity thickness δ at the trailing edge of the splitter was 13,500 for the pure water mixing-layer flow. Aquesous (200 ppm) Polyacrylamide (PAM) solutions and pure water were used as the liquid phase, and gas bubbles with a 0.5% void fraction were injected into the mixinglayer containing polymer additives, from the center of the splitter end, to check the influence of polymer additives and bubbles on the turbulent structure and properties. The distribution of the turbulence properties changed more significantly for the mixing-layer in the polymer additive case than in the pure water case. In the latter case, the Reynolds shear stress (RSS) peak was less than that for the pure water case at the same downstream cross section, but the vorticity peak in the polymer additive case was larger than that in the pure water case in the region the mixing-layer developed (x < 5δ). However, upon bubble injection, the effect of the polymer additives was diminished.


A novel multi-scale edge detection technique based on wavelet analysis with application in multiphase flows

August 2010

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141 Reads

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41 Citations

Powder Technology

A novel non-linear weighted statistical algorithm for multi-scale edge detection of gray image based on wavelet analysis is proposed to extract interface in multiphase flows. In this method, local modulus maximum of gray gradient along the phase angle direction is regarded as the possible edge (interface) of an image. A two-dimensional discrete Gaussian function with zero average value is adopted as smoothening filter. The influences of filter length, scale and threshold on the extracted edges are discussed in detail. In order to realize multi-scale detection, the local maximums of the wavelet transform modulus calculated under a series of the wavelet transform scales are used to detect the possible edge (interface) of an image. A modified Gaussian function is suggested to weight non-linearly those possible edges (interfaces) detected on different scales and a statistical function is proposed to synthesize the possibility of each pixel being edge over all scales. Compared with Canny operator, this new algorithm can extract the edge perfectly even with strong noise and light reflection, which shows the potential to extract the interface in multiphase flows.


Effects of velocity ratio on turbulent mixing layer at high Reynolds number

March 2009

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32 Reads

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7 Citations

Journal of Physics Conference Series

In this paper the effect of velocity ratio on plane mixing layer was experimentally investigated by Particle Image Velocimetry (PIV). The velocity ratio between low and high speed side are 0.25 and 0.50, respectively. The Reynolds number based on the velocity difference of two streams and hydraulic diameter of the channel is 66000. The results indicate that the maximum mean Reynolds stress on the same cross section is decreasing with the velocity ratio increasing. The maximum dimensionless mean vorticity is decreasing according to an exponential law along the stream-wise direction and the decreasing speed of dimensionless mean maximum vorticity is increasing with the velocity ratio increasing. The dimensionless vorticity caused by plate wake is decreasing sharply in a very short distance along the down stream wise direction and the decreasing speed is faster when the velocity ratio is larger.


Experimental Research on Turbulent Mixing Layer Flow with Polymer Additives

November 2008

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7 Reads

We present the results of an experimental study of fluids with polymer additives mixed by a specially designed splitter plate in a vertical rectangular channel. This arrangement is perhaps the simplest in which mixing effects can drive instability in the fluid. The velocity ratio between high and low speed is 4:1 and the Reynolds number based on the velocity difference of two steams and hydraulic diameter of the channel ranges are from 22800 to 87120. The flow field and turbulent parameters of different concentration polymer additives are measured and compared with water flow, which shows that the dynamic development of mixing layer is great influenced by polymer addictives. Our investigations reveal that similar with pure water case, the Reynolds stress and voticity still concentrate in a coniform area of central mixing flow field part. But compared with pure water case, the coniform width of polymer additives case is larger which means the polymer additives will lead to the diffusion of coherent structure. The peak value of vorticity in different cross section will decrease with the development of mixing layer. Compared with pure water case, the vorticity is larger at the beginning of the mixing layer but decreases faster.


Edge Detection Based on Wavelet Analysis with Gaussian Filter

January 2008

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102 Reads

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5 Citations

Fude Guo

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Yahui Yang

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Tao Ning

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[...]

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Lieijin Guo

In this paper an edge detection algorithm base on wavelet transform with Gaussian filter was proposed. In this algorithm original images are firstly converted into gray images and then each pixel was analyzed using wavelet transform to find the local maximum of the gray gradient of each pixel along the phase angle direction and compared with a given threshold value, through which real edge can be kept and fake ones will be eliminated. In the computation of local maximum, the gray gradients computed in eight directions, which can improve precision of edge detection. After the investigation of influence of filter length, scale and threshold value on the edge detection the proposed algorithm is validated by the comparison with N.L. Fen?ndez-Garc?a’s Minimean and Minimax methods for 100 real color images. The extraction result is more close to the real image which indicates the algorithm is effective and can be used to extract edges in different research areas.


Edge Detection Based on Wavelet Analysis With Gaussian Filter and Application in Multiphase Flow

January 2008

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9 Reads

In this paper an edge detection algorithm based on wavelet transform with Gaussian filter was proposed. In this algorithm original images are firstly converted into gray images and then each pixel was analyzed using wavelet transform to find the local maximum of the gray gradient of each pixel along the phase angle direction and compared with a given threshold value, through which real edge can be kept and fake ones will be eliminated. In the computation of local maximum, the gray gradients computed in eight directions, which can improve precision of edge detection. After the investigation of influence of filter length, scale and threshold value on the edge detection and validation by comparison with N.L. Fenández-García’s Minimean and Minimax methods for 100 real color images, we applied this algorithm to bubbly gas-liquid two-phase flow. Compared with Canny operator, present result is more close to real bubble shape and can distinguish very close bubbles, which indicates the algorithm is effective and can be used to study the interaction between different phases and flow field in multiphase flow.


PIV Experimental Investigation of a Single-Phase Turbulent Mixing Layer

November 2007

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9 Reads

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1 Citation

In this work single-phase turbulent mixing layer was investigated by PIV at three different velocity ratios. The results show that average vorticity along the streamwise central line decreases with the development of shear layer, and the decreasing speed is faster at the higher velocity ratio. Comparison of the average vorticity distribution on different cross section at similar Reynolds number indicates that the vorticity has a peak value at the high speed side and a vale value at the low speed side near the split edge. The interesting thing is that both of the peak and vale value decreased with the velocity ratio increasing for similar Reynolds numbers. Reynolds stress distribution along different cross-section of the mixing layer is increased with the increasement of the velocity ratio.


PIV Experimental Investigation of a Bubbly Turbulent shear Layer

November 2007

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7 Reads

In this work bubbly shear layer was investigated by PIV. The velocity ratio is 4:1 and the Reynolds number ranged from 22000 to 158400. PIV results show that almost all the bubbles are trapped by vortex structures. Compared with the single phase case, average vorticity changes little along the streamwise central line, but decreased with the increasement of Reynolds number. The average vorticity distribution along different cross-section of the shear layer is decreased at low Reynolds number but changes little at higher Reynolds number. The results indicate that Reynolds stress along different cross-section of the single phase case is increased with the development of shear layer but decreased with the increasement of Reynolds number, and this tendency is disordered with bubbles injection.

Citations (4)


... The Radon Transform (Boe, 2012;Krylov and Nelson, 2014) is advantageous for detecting linear structures but is less effective with curvilinear patterns. The CWT (Guo et al., 2010;Tu and Karstoft, 2015;Zhou et al., 2023) excels at multi-scale feature extraction but relies on fixed parameters, which may reduce adaptability across different geological contexts. Kokinou (2014, 2015) demonstrated the effectiveness of applying topology and shape optimization techniques to distinguish geological faults from similar geomorphological structures. ...

Reference:

Curvilinear Lineament Extraction: Bayesian Optimization of Principal Component Wavelet Analysis and Hysteresis Thresholding
A novel multi-scale edge detection technique based on wavelet analysis with application in multiphase flows
  • Citing Article
  • August 2010

Powder Technology

... Gaussian filters exhibit the same degree of smoothness in all directions, an advantage when dealing with images with an unknown edge direction (Fude et al., 2008). However, the filter processes the whole image uniformly, which can create dissimilarities due to the non-linear distribution of image intensities (Seddik et al., 2014). ...

Edge Detection Based on Wavelet Analysis with Gaussian Filter
  • Citing Article
  • January 2008

... A number of groups employed Particle Image Velocimetry (PIV), where Li et al [47] measured simultaneously with PIV and hot wire anemometry (HWA) for determining the optimum mode of operation. Guo et al. [48] used PIV for investigating the influence of the velocity ratio on the near field in the developing mixing layer. The group of Buxton and co-workers [49][50][51] studied the convection speed of fluctuations of different scales and their interaction in the far-field of an incompressible mixing layer by means of PIV. ...

Effects of velocity ratio on turbulent mixing layer at high Reynolds number
  • Citing Article
  • March 2009

Journal of Physics Conference Series