# Sinusoidal Expression

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 April 2, 2014, 14:17 Sinusoidal Expression #1 New Member   Luke Osborne Join Date: Apr 2014 Posts: 2 Rep Power: 0 Hi, I'm modelling a tank rotating using Cfx. the tank rotates with a mixture of water and air. A model is shown here http://i.imgur.com/wxdm3O6.png (the front and back faces are symmetry and the sides are free slip walls) The expression I am using to rotate the tank in alternate directions is if((t-tOn)>=0 [s], 0.3[rad s^-1]*sin((t-tOn)*2*pi/(4 [s])),0 [rad s^-1]) where tOn is a timestep of 0.075 [s] which results in a change of angular velocity as shown http://i.imgur.com/gjYPjCy.png However I would like to pause the sinusoidal wave at its positive and negative peaks for a period (lets say 1 [s]) how can i modify my expression to do this? If there is a way to make a plus or minus sign I can modify my expression to do this, is this possible? or what other ways could I do this? Thanks in advance, Luke

 April 2, 2014, 17:46 #2 Senior Member   Bruno Join Date: Mar 2009 Location: Brazil Posts: 277 Rep Power: 20 There are two ways to do that: 1) Generate the equation that does what you want, that is, use a sinusoidal wave for a period, then switch, to constant, then back to sinusoidal. or 2) Create a table of your expression in Excel as a function of time and use that table as a 1D function in Pre. This might be an easier way to do it. LukeOsb likes this.

 Tags cfx, flow, mixture, rotation, sinusoidal