![]() ![]() When there is turbulence, the layers mix, and there are significant velocities in directions other than the overall direction of flow. Layers flow without mixing when flow is laminar. (credit: Creativity103)įigure shows schematically how laminar and turbulent flow differ. If you watch the smoke (being careful not to breathe on it), you will notice that it rises more rapidly when flowing smoothly than after it becomes turbulent, implying that turbulence poses more resistance to flow. The smooth flow is called laminar flow, whereas the swirls and eddies typify turbulent flow. In short, fluid dynamics are complicated and there's not an easy way to look at a spout and determine if it will pour smoothly or not.\): Smoke rises smoothly for a while and then begins to form swirls and eddies. Reynolds number assumes a perfectly smooth surface any small bumps or roughness will break up the flow and cause turbulence. I'd imagine the surface roughness of the inside of the spout has a big impact too. the pour angle and hydrodynamic pressure (how much of the weight of the water still in the teapot is pressing on the water leaving the spout). The characteristic length for pipe flows (the spout) is the diameter and the velocity will depend on the geometry of the teapot, i.e. ![]() ![]() In the case of a teapot, the fluid density and viscosity will be the same for all of them. Reynolds number is a function of fluid density, velocity, viscosity and characteristic length. The laminar flow regime is generally Re < 2000. Reynolds number (Re) is a dimensionless number defined as the ratio between dynamic pressure (the force pushing the water forward) and shearing stress (the friction force preventing the water from moving forward). Reynolds number is a good predictor of if a flow will be laminar or turbulent. I'm sure there are engineers here who can give you a better/more correct answer, but here's my best guess. I am by no means an expert on fluid dynamics and all of this is based on exactly one undergraduate fluids class. We spent a lot of time fine tuning and refining. For laminar flow nozzles we used a cylinder with the nozzle in the concentric with very sharp and square plate. In a teapot you only have hydrostatic flow so the shape and head pressure of the teapot has to be in a sweet spot for the nozzle to create slug flow, following the rules above you also want a shape of vessel that doesn't create asymetric flow and thus turbulence. In that last example you actually want a subset of laminar flow called slug flow. The nozzle is also important from a standpoint of orifice size.įinal variable is flow rate. I believe our nozzles used a ~80 deg countersink that was machined to a knife edge. Next important that most people forget is the nozzle, you actually want a really sharp edge with a defined edge that has no burs, this makes sure no turbulence, flow separation etc is put in right before it comes out. The easiest shape to get laminar flow is a cylinder as there are no corners that create turbulence, the inside walls also have to be very smooth and uniform as even rough texture, burs or divots can create flow separation. This of course is much easier said then done. Laminar flow is all about getting water where the fluid is all going in the exact same direction with no turbulence. I can add some depth! I worked at a fountain company that did laminar flow fountains and I have a patent on some miniature laminar flow devices. Limit the use of engineering jokes.Ĭall for Engineers: Tell us about your job! (16 July 2020)Ģ020 List of engineers willing to be interviewedĢ019 List of engineers willing to be interviewed No low-effort one-liner comments, memes, or off-topic replies. Answers must contain an explanation using engineering logic, and assertions of fact must be supported by links to credible sources.īe substantive. Racism, sexism, or any other form of bigotry will not be tolerated.ĭon't answer if you aren't knowledgeable. All users are expected to behave with courtesy. Note that questions must still be specific to engineering and not a general opinion survey.īe respectful to other users. Mechanical, Electrical, Civil, Chemical, and Computer are reserved for technical questions only.ĭiscussion can be used for general questions that apply to multiple disciplines, including some workplace topics. Review the wiki prior to posting.Īvoid questions that can easily be answered by searching on the internet.Īvoid questions that have already be answered by a post in the FAQ section of the wiki. Most general career related questions should be placed in the Monday Career Megathread. Post titles must be a question about engineering and provide context - be specific. Call for Engineers: Tell us about your job! (2020) New to AskEngineers? Read our subreddit rules and FAQ page before posting! Topic Filters ![]()
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