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Dr. Xia Wang Assistant Professor Department of Mechanical Engineering

Contact Information:. Dr. Xia Wang Assistant Professor Department of Mechanical Engineering Tel: 248-370-2224 Fax: 248-370-4416 Email: wang@oakland.edu. Turbulent Boundary Layer with separation by Dr. Xia Wang. Adverse Pressure Gradient (APG). U 0. U 0. Zero pressure gradient

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Dr. Xia Wang Assistant Professor Department of Mechanical Engineering

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  1. Contact Information: Dr. Xia Wang Assistant Professor Department of Mechanical Engineering Tel: 248-370-2224 Fax: 248-370-4416 Email: wang@oakland.edu

  2. Turbulent Boundary Layer with separation by Dr. Xia Wang

  3. Adverse Pressure Gradient (APG) U0 U0 Zero pressure gradient (ZPG) Favorable pressure gradient (FPG) Reverse Flow Reverse Flow U(x,y) U(x,y) d(x) d(x) Separation Separation xo TBL-with separation

  4. TBL separation is everywhere Turbine Blade Flow around a car Taken from (Hucho and Sovran 1993) Diffuser

  5. Research Interests • Can we characterize the turbulent boundary layers with eventual separation? • How to predict the separation position? • How can this instruct the car body design?

  6. Coherent structure ITD D ID Detached flow ID: Incipient Detachment 1% ITD: Intermittent Transitory Detachment 20% TD: Transitory Detachment 50% D: Detachment Cf=0.0 TBL Separation is an event!

  7. Research Approach-Similarity Analysis • The scales for the turbulent boundary layer flow are dictated by the equation and its boundary conditions alone. • In the limit as Re, the equations of motion become independent of Re. Thus any scale or function expressing the solutions must also be independent of Pe. (Asymptotic Invariance Principle: AIP, George & Castillo 1997)

  8. Research Approach-Similarity Analysis • Apply similarity analysis to RANS

  9. Pressure parameters

  10. Separation Criterion • Integral Momentum Equation • Replacing the PG parameter from the similarity analysis • At separation: Cf0 Hsep=2.76 0.23

  11. Results-1 TBL without separation TBL with separation

  12. Consistent with Industrial Practices Hall (2003) : To avoid separation on compressor blades, Hsep<2.5 Elsberry et al (2000): To keep an equilibrium on the verge of separation, Hsep<2.6 Consistent with Measure Results Sandborn & Kline (1961), Kline et al (1983), Sajben & Liao (1995) Hsep=2.7 for the intermittent detachment. Fernholz & Alving (1990) : Hsep=2.850.1 Alving & Fernholz (1996) : Hsep=2.78 Results-2

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