Wall shear-stress extraction by an optical flow algorithm with a sub-grid formulation

Chen, Lin

doi:10.1007/s10409-020-00994-9

Cited by 11 publications

(8 citation statements)

References 37 publications

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“…In this study, we proposed a hybrid method for the estimation of flow around the jet model. Difference to the previous study, the optical-flow algorithm was adopted from our previous study, which was used for skin-friction analysis [16]. We show that the hybrid method provides good results in comparison to the optical-flow algorithm.…”

Section: Introductionsmentioning

confidence: 90%

“…The details of the method for solving Eq. ( 4) were presented in the previous study by Tran and Chen [16]. The main difference between the current algorithm and previous studies is that the initial velocity is chosen as velocity from PIV results in the current study by comparison to zero value in [16].…”

Section: Optical-flow Algorithm For Velocity Refinementmentioning

confidence: 99%

“…The optical-flow algorithm used in this study was based on the global optical-flow algorithm proposed by Horn and Strunck [21] with additional modifications proposed by Cassian et al [22], Chen et al [23], and Tran and Chen [16]. In detail, the equation showing the motion of particles in the measurement image can be written below: 12 ( ) ( , , ) where  is the gradient operator, I is the intensity of the image, u is the velocity vector and f is a function including all outer parameters such as laser thickness and setup of the laser.…”

Section: Optical-flow Algorithm For Velocity Refinementmentioning

confidence: 99%

“…( 4) were presented in the previous study by Tran and Chen [16]. The main difference between the current algorithm and previous studies is that the initial velocity is chosen as velocity from PIV results in the current study by comparison to zero value in [16]. Generally, a similar hybrid approach was used by Yang et al [14] and Liu et al [15].…”

Section: Optical-flow Algorithm For Velocity Refinementmentioning

confidence: 99%

See 3 more Smart Citations

Optical-Flow and Cross-Correlation Algorithms for Analyzing Jet Flow

Hùng¹,

Anh²,

Văn³

2022

TNUJST

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Xử lý dữ liệu nhằm thu được trường vận tốc toàn cục rất quan trọng trong cơ học chất lỏng.Nghiên cứu này trình bày thuật toán lai để trích xuất véc tơ vận tốc từ ảnh của phương pháp đo vận tốc ảnh hạt (PIV) thực hiện trong quá trình thực nghiệm. Phương pháp lai sử dụng cả thuật toán tương quan chéo và thuật toán xử lý ảnh. Đầu tiên, thuật toán tương quan chéo được sử dụng để trích xuất vận tốc ban đầu từ ảnh PIV. Sau đó, thuật toán xử lý ảnh được áp dụng cho các trường vận tốc đã được tinh chỉnh với ước lượng ban đầu bằng kết quả tương quan chéo. Phương pháp đề xuất được áp dụng cho phân tích véc tơ vận tốc từ dòng chảy qua vòi phun. Kết quả chỉ ra rằng phương pháp lai thấy hình ảnh tương tự với thuật toán tương quan chéo. Ngoài ra, độ phân giải đã được cải thiện nhiều bởi thuật toán được đề xuất so với kết quả từ phương pháp tương quan chéo. Cả trường vận tốc trung bình và vận tốc tức thời được phân tích trong nghiên cứu này. Ảnh hưởng của hệ số Lagrange, số bước lặp tính toán lên kết quả của phương pháp lai được khảo sát. Phương pháp được đề xuất cho thấy hiệu quả cao trong việc trích xuất trường vận tốc từ ảnh PIV.

show abstract

Section: Introductionsmentioning

confidence: 90%

Section: Optical-flow Algorithm For Velocity Refinementmentioning

confidence: 99%

Section: Optical-flow Algorithm For Velocity Refinementmentioning

confidence: 99%

Section: Optical-flow Algorithm For Velocity Refinementmentioning

confidence: 99%

See 2 more Smart Citations

Optical-Flow and Cross-Correlation Algorithms for Analyzing Jet Flow

Hùng¹,

Anh²,

Văn³

2022

TNUJST

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show abstract

“…The methods, consequently, are still widely applied in many recent studies [2,3,[11][12][13][14]. The numerical studies also allow to extend results from experimental methods, which are often limited by measurement devices [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Influence of Spike-Nosed Length on Aerodynamic Drag of a Wing-Projectile Model

Van,

T.,

Xuan

et al. 2022

AiMT

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In this study, the effect of spike-nosed length on aerodynamic drag of a wing-projectile model was investigated at supersonic conditions. The projectile BK-13 with convex nose was selected for the study. The ratio of nose diameter and model diameter was fixed at around 0.34 while the ratio of the length of the nose and the model diameter was changed from 1.25 to 2.75. Numerical simulation with turbulent model k-ε was applied for flow structure around the model. The effect of mesh size and numerical models on the drag of the standard model was investigated. The study showed that numerical methods allow to obtain highly accurate drag coefficients. As the length of aerospike increases, the drag coefficient quickly decreases and obtains a minimum value at l/D = 2.0. The effect of spike-nosed length and velocity on flow pattern and drag of the model was ex-plained in details in this study

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Determining Objects Surface and Its Characteristics by Mathematical Approach

Nguyen

Tran

2022

Lecture Notes in Mechanical Engineering

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Wall shear-stress extraction by an optical flow algorithm with a sub-grid formulation

Cited by 11 publications

References 37 publications

Optical-Flow and Cross-Correlation Algorithms for Analyzing Jet Flow

Optical-Flow and Cross-Correlation Algorithms for Analyzing Jet Flow

Influence of Spike-Nosed Length on Aerodynamic Drag of a Wing-Projectile Model

Determining Objects Surface and Its Characteristics by Mathematical Approach

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