Bentley Hammer_Error

Hello Videet,

The red error notifications implies that the pressure is less in the initial conditions itself before performing transient calculations, please check the pressure at junctions in the initial conditions. The occurrence of sub-vapor pressure in the initial conditions means that you would actually have a vapor pocket at that location, before the transient event even starts. 

User Notification "Initial pressure less than vapor pressure. At the pipe end(s), the elevation(s) or head(s) are incorrect" 

About notification of lengths, it just notifies that there are either too short or too large pipe lengths in the model, the below technote explains this in detail, please go through it. 

Understanding length/wave speed adjustments and their impact on results 

After performing some operations I am still not able to solve it.

I am sharing the model with you. Can you please have a look and guide me.

Thank you.

Hammer_1.rar

You can refer this also as it is with some more corrections.

I am not able to solve the notification, "Initial pressure less than vapor pressure. At the pipe end(s), the elevation(s) or head(s) are incorrect." for 6 nos. of pipe.

Thank you.

Hammer_2.rar

Hello Videet,

I checked your latest model. When "Initial Conditions" are computed I am getting a User Notification as "Pressures below the lowest physically possible at one or more time steps". I checked in your model and found several junctions towards the end of your rising main with negative pressures. The "Initial Conditions" are computed to ensure that the model is hydraulically sound before a transient analysis is performed. It helps in identifying such problems with the model.

Here is a relevant article in this regard;

Troubleshooting negative pressures at pumps, junctions, & other node elements

Also you can refer the following article to learn how to prepare a hydraulic model before performing transient analysis.

Preparing an existing model for a transient analysis in HAMMER

Hope this helps.

Regards,

Yashodhan Joshi

Bentley Technical Support

To add to my colleagues' responses:

If you extend your profile to the downstream end of the system and open the profile, you will see a local high point near the end of the system (near J-478) where the HGL is below the physical elevation.

In the real system, if you have an air valve at this local high point, the pump may be adding more head to "lift" the water up to the high point, with partially-full flow downstream of it. For the purposes of a transient simulation, if there is an air gap during the normal operating conditions (the initial conditions before your transient event), then you may want to end the system at the top of the high point at the air valve location, simulating it as a Discharge-to-Atmosphere element.

This situation is mentioned in the article that Sushma linked to, which I have just enhanced a bit - see the section "Local high points".

User Notification "Initial pressure less than vapor pressure. At the pipe end(s), the elevation(s) or head(s) are incorrect"