Hellowhen I modeling transient event , in some points the maximum transient pressure is the same as steady state , what is the meaning of this?is there something wrong
Hello Adnan,
For the parts of the profile where the max transient head is equal to the initial conditions head, it means that the HGL during the transient simulation never went above the initial conditions HGL. This could be due to a number of different reasons, either "real", or due to some problem. Since the minimum pressure seems to be equal to the vapor pressure limit for most of the profile, most likely you are modeling a transient event that results in a "downsurge" wave throughout the profile in question and the pressure never rises back up for most of the network before the end of the simulation. The parts of the profile on the right side may experience vapor pocket collapse, causing an "upsurge" wave from the water columns colliding, resulting in the pressure rising up, above the initial pressure.
See more in the video below.
I would recommend animating the profile using the green play button at the top, to better visualize what is happening here. If this does not help, please compress the .WTG and .SQLITE files into a zip file and upload using one of the methods below:
Sharing Hydraulic Model Files on the Haestad Forum
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Answer Verified By: Adnan Draweel
System A-B ( After Modeling TRANS.) TIme ste LAST GG.wtg.zip
System A-B ( After Modeling TRANS.) TIme ste LAST GG.zip
For first part of the profile in your model where max pressure reached is not above the initial conditions because you are observing downsurge in that part of the model. Upsurge is not seen till pipe A.150 so maximum pressure is not above the initial conditions.
Whereas upsurge and vapor pocket formation are observed beyond 8 seconds in this transient event of pump shut down in second part of the profile. As mentioned by Jesse in his previous reply please animate the profile using the green play button at the top, for better visualization.
There is user notification about wave speed because of short pipes in your model. Please go through below mentioned wiki to understand that.
Understanding length/wave speed adjustments and their impact on results
Sushma Choure
Bentley Technical Suppport