I don't think "time" is appropriate in this case, as you said your object will be displaced with same amount of value in time, you won't get wave kind displacement.$height * sin( $freq * time )
The 3.14 value, my teacher said is approximately a PI constant. So in this case the total wave it's about 5 complete sine wave (1 cycle should be 2 * PI).sine_ramp.alphaGain = sin(place2dTexture1.vCoord * 10.0 * 3.14);
you will get some animation of the wave.sine_ramp.alphaGain = sin((place2dTexture1.vCoord + (time/50)) * 10.0 * 3.14);