When a vacuum is generated next to a turbulence, does the flow towards the vacuum become laminar? Imagine a vacuum cleaner tube is put next to turbulent air movement, does the "suction" change the turbulent air flow to a laminar one?
[Physics] Can a vacuum make a turbulent flow laminar
fluid dynamicsturbulencevacuum
Related Solutions
For Newtonian fluids (such as water and air), the viscous stress tensor, $T_{ij}$, is proportional to the rate of deformation tensor, $D_{ij}$:
$$D_{ij} = \frac{1}{2}\left(\frac{\partial v_i}{\partial x_j} + \frac{\partial v_j}{\partial x_i}\right)$$
$$T_{ij} = \lambda\Delta\delta_{ij} + 2\mu D_{ij}$$
where $\Delta \equiv D_{11} + D_{22} + D_{33}$. The Navier-Stokes equation for Newtonian fluids can then be written as:
$$\rho\left(\frac{\partial v_i}{\partial t} + v_j\frac{\partial v_i}{\partial x_j}\right) = -\frac{\partial p}{\partial x_i} + \rho B_i + \frac{\partial T_{ij}}{\partial x_j}$$
The Navier-Stokes equation above governs both laminar and turbulent flow using the same stress tensor. This shows that the definition of shear rate is the same in both laminar and turbulent flows, however, their values will be very different.
For non-Newtonian fluids, the same is true. Instead of the stress tensor defined above, replace it with a non-Newtonian stress tensor. Still the same governing equation applies to laminar and turbulent flows so the definition of shear rate is the same for both regimes.
As you mention, turbulent flow does not have nice, orderly layers. As a result, there can be acute stress localizations.
Either kind of flow can exhibit steady flow or unsteady flow. Unsteady flow is where, over a large time scale, things are changing at each spatial location with time. When they say that turbulent flow is inherently unsteady, what they mean is that, over a small time scale (at each spatial location), the velocity components are varying rapidly with time, but, when averaged over relatively small time intervals, the average velocity components vary much more slowly, or not at all. If they do not vary at all, the turbulent flow is considered steady. If the vary slowly (at each spatial location) the turbulent flow is considered unsteady.
Regarding inviscid flow, it is assumed that viscous and turbulent stresses are both considered insignificant. So it is considered neither laminar nor turbulent. It would be what you would obtain if the fluid had a very low viscosity, but the flow could not transition to turbulent flow.
Best Answer
Just adding a sink somewhere will not change the nature of the flow. The flow is characterized by characteristic lengths and velocities, and material properties. These can be combined to give the Reynolds number, which is indicative of the likeliness of transition to turbulence. If you add a sink, you will only possibly modify the characteristic velocity difference, but it may be difficult to decrease it significantly without altering the function of whatever device you study.
Then, in very specific cases, you can reduce velocity difference: this has been applied to boundary layers in boundary layer suction (link) techniques. Basically, by sucking air at the surface of a wing, you reduce the difference of velocity between the bulk of air flow and air close to the wing (zero without suction). As you can understand, each geometry and flow parameters need a separate study to determine whether this will work: so there is no principle saying that vacuum will reduce turbulence.