Toothpaste was originally packed in different colors, but toothpaste belongs to The Bingham fluid (a non-Newtonian fluid), that is, it has a solid nature (does not flow randomly) and a liquid property (there is thunder

Toothpaste is originally different colors are installed separately, but toothpaste belongs to Bingham fluid (a kind of non-Newtonian fluid), that is, there is a solid property (will not flow randomly) and a liquid property (there is a Reynolds number), the Reynolds number is a coefficient that indicates the viscosity of the fluid, because the toothpaste Reynolds number is less than 2300, so it will produce laminar flow phenomenon, that is, different colors of toothpaste will not mix, no matter how to squeeze and rub, his color will still be blue and white, so when extruded, it is not mixed.