blade moment inside a box

Submitted by Gulniamat on Thu, 08/25/2016 - 12:00

Hello every one.... i am new to LIGGGHTS, I am trying to simulate a phenomenon where a blade is moving inside a box from one end to other end. Particles are there inside the box upto the blade height. Is there any command in LIGGGHTS which i can use to produce multiple passes of blade. Currently the blade move from one end to other and stop there, i want to move blade back and forth 15 time between the two ends. Kindly if any one has the idea then guide me. Thanks

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Maryam | Thu, 08/25/2016 - 20:53

Use "fix move/mesh" with the "wiggle" option. Set the amplitude and period in accordance to the blade's velocity and box's length.

Maryam

Gulniamat | Fri, 08/26/2016 - 08:04

Thanku Maryam...
Maryam my Box's length is 1.2 meter and i want to move the blade with 0.15 m/s. Now please help me how much i have to set amplitude and how much i have to set period. Kindly help me with complete command line if u have time to write it for me, i will be very thankful to you.

Maryam | Mon, 09/12/2016 - 20:24

First you should move the blade to the center of the box. Assuming the length of your box in the x-direction and the blade starts to move in the +x direction:

fix moveLinear all move/mesh mesh meshName linear 0.15 0 0
variable ts equal 1e-8 # timestep
timestep ${ts}
variable steps equal 1.2/(2*0.15${ts})
run ${steps}

Now you should introduce the periodic motion of the blade:

unfix moveLinear
variable p equal 1.2*2/0.15 # period
fix moveWiggle all move/mesh mesh meshMoved wiggle amplitude 0.6 0. 0. period ${p}

Of course the velocity of the blade will not remain constant during the course of its motion. You should also move the blade to the middle of the box before starting to wiggle, by redefining the fix mesh/surface command with the "move" option.

Maryam