We\u2019ve all been there\u2026 a beautiful summer\u2019s day, burger in hand and then the great tradition starts of trying to apply ketchup! Do you bash the bottle trying to get some out or shake it gently? Whatever you choose the inevitable will happen, initially nothing, and then suddenly a great big dollop of ketchup will come flying out, miss the burger and end up all over your clothes!<\/p>\n\n\n\n
Ketchup is a weird\nfluid, however we don\u2019t often think about this too much in everyday life. Scientists\nand engineers encounter this in a number of scenarios though and must try to\nunderstand these types of fluids to create successful solutions. <\/p>\n\n\n\n
To better understand\nthis weirdness, try to imagine a glass ketchup bottle, but instead of it being\nfilled with ketchup it is filled with a solid, say concrete for example. You\ncould shake that bottle all day and the only way you would get it out is by\nbreaking the bottle. If we take the same example but fill the bottle with\nliquid, let\u2019s choose water, when we tip the bottle over the water will just\npour out easily. Ketchup shows a combination of these two behaviours, so if you\nwere asked to describe it, would you call it a solid or a liquid? The correct\nanswer to this is that it has properties of both so we would usually refer to\nit not by its state but by calling it a fluid.<\/p>\n\n\n\n
Regular fluids such as\nwater and oil respond to force linearly. Imagine you have a plastic bottle\nfilled with water, if you push on the sides you can make the fluid flow, if you\npush twice as hard the fluid will move twice as fast. The technical name for\nthese are Newtonian fluids.<\/p>\n\n\n\n
Now what about the fluids that don\u2019t follow this rule. Well these are Non-Newtonian fluids. We encounter these often in our everyday lives but don\u2019t often give them much thought. Examples of these are mayonnaise, custard, honey, toothpaste, paint, blood, shampoo, slime<\/a> (which you may remember from our previous blog post) and our favourite\u2026 ketchup. <\/p>\n\n\n\n