Viscoelastic laminar drag bounds in pipe flow

Distinct large-scale turbulent-laminar states in transitional pipe flow.

When fluid flows through a channel, pipe, or duct, there are two basic forms of motion: smooth laminar motion and complex turbulent motion. The discontinuous transition between these states is a fundamental problem that has been studied for more than 100 yr. What has received far less attention is the large-scale nature of the turbulent flows near transition once they are established. We have c...

Entropy Generation in Laminar Fluid Flow through a Circular Pipe

A numerical solution to the entropy generation in a circular pipe is made. Radial and axial variations are considered. Navier-Stokes equations in cylindrical coordinates are used to solve the velocity and temperature fields. Uniform wall heat flux is considered as the thermal boundary condition. The distribution of the entropy generation rate is investigated throughout the volume of the fluid a...

Viscoelastic effects on drop deformation in a converging pipe flow

his paper reports finite-element simulations of drop deformation in converging flows in an xisymmetric conical geometry. The moving interface is captured using a diffuse-interface model nd accurate interfacial resolution is ensured by adaptive refinement of the grid. We have explored he effects of viscoelasticity on drop deformation when either the drop or the matrix is a Giesekus uid. Contrary...

Modeling of viscoelastic turbulent flow in channel and pipe

A viscoelastic model of shear-induced hemolysis in laminar flow.

We present measurements of human blood hemolysis caused by laminar shear stresses ranging from 50 to 500 Pa for exposure times extending from 60 to 300 s using a Taylor-Couette device. A viscoelastic model is proposed that captures the response of the red blood cells to shear stress. The model is based on well-established mechanical properties of the red blood cell membrane, and shows good agre...