CFDa.4.viscous

CFDa.4.viscous - Fluids Review TRN-1998-004 Boundary-Layer...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
© Fluent Inc. 12/05/10 D1 Fluids Review TRN-1998-004 Boundary-Layer and Viscous Flows
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
© Fluent Inc. 12/05/10 D2 Fluids Review TRN-1998-004 Overvie w Introduce the concept of the Boundary-Layer Introduce the Boundary-Layer Equations Laminar to Turbulence Transition Turbulent Boundary Layer Flow Separation
Background image of page 2
© Fluent Inc. 12/05/10 D3 Fluids Review TRN-1998-004 The Boundary-Layer Concepts (1) Prandtl (1904) introduced the concept of the boundary layer. The boundary layer is defined as the thin region on the surface of a body in which viscous effects are important. The fluid in the region outside the BL behaves as if inviscid (inertial dominated). The viscous effects, fluid friction, typically occur in flows at high Reynolds numbers. Using the above hypothesis, it is possible to simplify the analysis of high Reynolds number flow allowing for the analytical solution of external flow problems.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
© Fluent Inc. 12/05/10 D4 Fluids Review TRN-1998-004 Boundary-Layer Concepts (2) The BL increases in thickness from the leading edge. Near the leading edge the flow is laminar At a certain distance x from the leading edge the flow becomes turbulent A laminar sublayer exists in the turbulent BL where the flow is laminar
Background image of page 4
© Fluent Inc. 12/05/10 D5 Fluids Review TRN-1998-004 The Boundary-Layer Concepts (3) The BL allows the fluid to transition from the free stream velocity U to a velocity of zero at the wall The BL thickness δ is defined as the distance away from the surface where the velocity reaches 99% of the free-stream velocity, 99 . 0 , = = δ U u where y
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
© Fluent Inc. 12/05/10 D6 Fluids Review TRN-1998-004 The Boundary-Layer Concepts (4) The BL displacement thickness δ is defined as the thickness of a zero- velocity layer which has the same mass flow defect as the BL - = δ 0 * 1 dy U u Equal Areas u = U μ = 0 u = u ( y ) = 0 δ u/U = 0.99
Background image of page 6
© Fluent Inc. 12/05/10 D7 Fluids Review TRN-1998-004 The Boundary-Layer Equations (1) The following analysis is for laminar flow The solution of a viscous incompressible flow past any object can be obtained
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 21

CFDa.4.viscous - Fluids Review TRN-1998-004 Boundary-Layer...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online