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difference between 'fpt.V' and 'fpt.vx'

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Hi everyone:
I use the fluid particle tracing module(fpt) to calculate the trace.
I want to know the differences between the 'fpt.V'(particle belocity magnitude) and the fpt.vx,fpt.vy,fpt.vz(particle velocity,x,y,z component) .
AND also what is the difference between the particle velocity and the negative particle velocity?


In the fpt module,I added no force but the default color expression showed that the 'fpt.V'(particle belocity magnitude) is 14.901e-9. It puzzled me.

Best regards!

3 Replies Last Post 07.11.2014, 10:03 GMT-5

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Posted: 1 decade ago 06.11.2014, 14:44 GMT-5
particle position: q
particle position components: qx, qy, qz
fpt denotes "particle tracing for fluid flow"
particle velocity, x component: fpt.vx = comp1.qxt, where comp1 denotes "component 1"
particle velocity, y component: fpt.vy = comp1.qyt
particle velocity, z component: fpt.vz = comp1.qzt
fpt.V=sqrt(comp1.qxt^2+comp1.qyt^2+comp1.qzt^2+eps)
-DW
particle position: q particle position components: qx, qy, qz fpt denotes "particle tracing for fluid flow" particle velocity, x component: fpt.vx = comp1.qxt, where comp1 denotes "component 1" particle velocity, y component: fpt.vy = comp1.qyt particle velocity, z component: fpt.vz = comp1.qzt fpt.V=sqrt(comp1.qxt^2+comp1.qyt^2+comp1.qzt^2+eps) -DW

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Posted: 1 decade ago 06.11.2014, 20:31 GMT-5
THANKS !
Why my vx=vy=vz=0 but fpt.V=14.901e-9? Because of the 'eps'?

And 'qxt' denotes qx * t ?
THANKS ! Why my vx=vy=vz=0 but fpt.V=14.901e-9? Because of the 'eps'? And 'qxt' denotes qx * t ?

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Posted: 1 decade ago 07.11.2014, 10:03 GMT-5
Hello,

qxt means the derivative of x-component of the position (qx) with respect to time t.

BR
Mohamed
Hello, qxt means the derivative of x-component of the position (qx) with respect to time t. BR Mohamed

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