wave in the pipe
 

Hi,
I solved the water hammer equations by method of characteristics for the pipe configuration.
Pipe is closed on both sides.
Initial values for the simulation are
velocity =0
sine wave is given as pressure signal for the first five nodes and remaining all nodes zero. I applied reflective boundary conditions at both the ends.
I got some simulation results. The wave is moving forward and it is not reflecting back ward at the other end. Pressure values is increasing as it is moving along the pipe and by the time it reaches the other end, pressure values becoming not a number.
Can any one tell me what could be the reason for this..
My requirement is to move pressure signal inside closed pipe and observe its behavior.

Thanks in advance