Concept explainers
Evaluate the displacement thickness δ* and the momentum thickness θ for a velocity profile given by
Want to see the full answer?
Check out a sample textbook solutionChapter 9 Solutions
Fox and McDonald's Introduction to Fluid Mechanics
Additional Engineering Textbook Solutions
Fundamentals Of Thermodynamics
Degarmo's Materials And Processes In Manufacturing
Applied Fluid Mechanics (7th Edition)
INTERNATIONAL EDITION---Engineering Mechanics: Statics, 14th edition (SI unit)
Thinking Like an Engineer: An Active Learning Approach (3rd Edition)
Fundamentals of Heat and Mass Transfer
- a. If the velocity distribution for the laminar boundary layer over a flat plate is given by :- ** (²) ² - 21 + A₂ x U A₁ + A₂ x Determine the form of the velocity profile by using the necessary boundary conditions. After that by using the Von-Karman integral momentum equation find an expression in terms of the Reynolds number to evaluate 1- Boundary Layer Thickness Force 2-Wall Shear Stress 3-Drag 5- Displacement Thickness + A₁ x 4- Local and Average Skin Friction Coefficients 6- Momentum Thickness 7- Energy Thicknessarrow_forwardhelparrow_forwardLocal boundary layer effects, such as shear stress and heattransfer, are best correlated with local variables, rather usingdistance x from the leading edge. The momentum thicknessθ is often used as a length scale. Use the analysis of turbulentflat-plate flow to write local wall shear stress τw in terms ofdimensionless θ and compare with the formula recommendedby Schlichting: Cf ≈ 0.033 Reθ -0.268.arrow_forward
- The velocity distribution in the boundary layer is given by :u/U=(y/δ)^0.23 where u is the velocity at a distance y from the plate and u=U at y=δ , δ being boundary layer thickness. Find: a-The displacement thickness .b- the momentum thickness .c- the energy thickness. d- Boundary layer shape factor .e- energy loss due boundary layer if a particular section. The boundary layer thickness is 28mm and the free stream velocity is 19 m/s. if the discharge through the boundary layer region is 8m3/s per meter width, express this energy loss in term of meters of head. Take ρ=1.2 kg/m3.arrow_forwardThe velocity distribution in the boundary layer is given by :u/U=(y/δ)^0.23 where u is the velocity at a distance y from the plate and u=U at y=δ , δ being boundary layer thickness. Find: a-The displacement thickness .b- the momentum thickness .c- the energy thickness. d- Boundary layer shape factor .e- energy loss due boundary layer if a particular section. The boundary layer thickness is 28mm and the free stream velocity is 19 m/s. if the discharge through the boundary layer region is 8m3/s per meter width, express this energy loss in term of meters of head. Take ρ=1.2 kg/m3arrow_forwardIBL, Flat Plate. Apply the integral boundary layer analysis to a flat plate turbulent flow as follows. Assume the turbulent profile u/U = (y/δ)1/6 to compute the momentum flux term on the RHS of IBL, but on the LHS of IBL, use the empirical wall shear stress, adapted from pipe flow: ?w = 0.0233 ⍴U2 (v/Uδ)1/4 where the kinematic viscosity ν = μ/⍴. It is necessary to use this empirical wall shear relation because the turbulent power law velocity profile blows up at the wall and cannot be used to evaluate the wall shear stress. Compute (a) (δ/x) as a function of Rex; (b) total drag coefficient, CD, L as a function of ReL; (c) If ReL = 6 x 107 compare values for this IBL CD,L and those empirical ones given in Table 9.1 for both smooth plate and transitional at Rex = 5 x 105 cases. Note: You must show all the algebra in evaluating the IBL to get full credit. Ans OM: (a) (δ/x) ~ 10-1/(Rex)1/5; (b) CD,L ~ 10-2/(ReL)1/5; (c) CD,IBL ~ 10-3; CD,Smooth ~ 10-3; CD,Trans ~ 10-3arrow_forward
- A vertical air stream flowing at a velocity of 100 m/s supports a ball of 60 mm in diameter. Taking the density of air as 1.2 kg/m³ and kinematic viscosity as 1.6 stokes, the weight of the ball that is supported is (if coefficient of drag C= 0.8)arrow_forward(a) Use the y-momentum equation to show that the pressure gradient across the boundary layer is approximately zero i.e. - 0. Assume the boundary layer to be a two-dimensional ду steady and incompressible flow. Neglect gravitational forces. State clearly all assumptions made. (b) Show that the x-momentum equation can be written as follows. dU + v- = U + dx ди du 1 дт dx ду рду where U is the free stream velocity. State clearly all assumptions made.arrow_forwardA pipe bore diameter D and length L has fully developed laminar flow throughout the entire length with a centre line velocity u0. Given that the drag coefficient is given as CD = 16/Re where Re = pu,D/µ. Derive the expression of the drag force on the inside of the pipe to be FD =8TTHU,L c. and hence show the pressure loss due to skin friction is pL = 32µu,L/D²arrow_forward
- Water flows at a velocity of 1.2 m/s over a flat plate 1.2 m long. Assume 1/7thpower law and determine the boundary layer thickness and displacementthickness. Compare the values with values calculated using laminar flowcorrelations. υ = 1 × 10−6m2/s.arrow_forwardConsider the boundary layer over a flat plate at 45° angle as shown. The exact flow field in this configuration is described by the Falkner-Skan similarity solution with n = 1/3 (see Figure 10.8 of the textbook, the Falkner-Skan profile chart). The objective is to find the approximate solution to this problem using the Thwaites method and calculate its error. Ve 11/4 Assume that for this approximate solution the free stream velocity is U₂(x) = ax" where a is an unknown constants and n = 1/3. Use the Thwaites method to find the momentum 0/x and 8*/x displacement thicknesses as well as the friction coefficient cf = 0.5, as functions of Re₂ = Uer/v, where is the shear stress at the wall. (No need to interpolate the Thwaites method table values; you can pick the nearest numbers.) Using the Falkner-Skan profile chart approximate the friction coefficient c; (by estimating the slope of the corresponding velocity profile at the wall). How does this value compare with your prediction in part…arrow_forwardQ4:- If the velocity profile for the laminar boundary layer is given by :- 24 -²)-¹()*+()* ² ( 2 ) - ² ( ² ) ² + ( ²3/ = 2 00 Starting from the integral momentum equation, find an expressions in terms of the Reynolds number to evaluate 1- Boundary Layer Thickness 2-Wall Shear Stress 3- Average Skin Friction Coefficient 4- Drag Force exerted on One Sidearrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY