# How Accurate is the Tait Equation of State?

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 August 4, 2004, 00:32 How Accurate is the Tait Equation of State? #1 Cary Kenny Guest   Posts: n/a So far Tait EOS is a standard EOS applied to water, particularly in the highly pressurised regime. The question is, how accurate is the Tait EOS when it is used to modelled region where the water pressure is negative (under tension)?

 August 4, 2004, 11:59 Re: How Accurate is the Tait Equation of State? #2 Angen Guest   Posts: n/a I think this equation has a simple mathematical form. Can you write it down for us? Andy

 August 4, 2004, 12:20 Re: How Accurate is the Tait Equation of State? #3 George Guest   Posts: n/a I'm not sure what do you mean by a "negative pressure", as strictly speaking there is no such thing in a fluid. Generally, if the (absolute) pressure decreases sufficiently, then you get phase change, i.e. cavitation. I think you need to better specify your problem. Regards, George

 August 4, 2004, 13:01 Re: How Accurate is the Tait Equation of State? #4 jasond Guest   Posts: n/a Water (and other liquids) can support some tension, or absolute pressures less than the vapor pressure, without phase change. The tensile strength is generally very small and depends on many factors. I could be mistaken, but I believe that the original poster is referring to pressure relative to the vapor pressure.

 August 4, 2004, 22:48 Re: How Accurate is the Tait Equation of State? #5 Cary Kenny Guest   Posts: n/a Thanks guys, your views are greatly appreciated. To redefine my earlier question, this is the scenario: Water, similar to solid, posses a tensile strength, i.e. ability to withstand distortion. For solid, e.g. if a metal bar is pulled from both end, the bar will resist to be pulled apart (here tension refers to negative direction of force, as compression refers to positive one). So is water, if a "bar of water" is pulled, it will resist to break, but due to cavitation nuclei, it is very common to see the water bar "break" easily - and produce cavitation. The tension produced by the decrease in total pressure is the reason, as Jasond said. In numerical simulations, Tait EOS is commonly used to represent "pure" water i.e. no cavitation exist in water, paticularly in the case of high pressure regime (<10GPa). But is Tait EOS still valid if inside the water there exist some pressure region of -10MPa? Thanks

 November 20, 2010, 03:23 How to Define Tait's Equation of State for water in Fluent #6 New Member   Bhaskar K Join Date: Nov 2010 Posts: 1 Rep Power: 0 How to replace the constant density value for water by Tait's Equation of state in fluent Last edited by bhaskarsharma; November 21, 2010 at 11:01. Reason: to be more precise

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