Transient Analysis of a Pipe Break & Hydrant Flushing

Hello Parsa, 

For both of this cases you can use discharge to atmosphere - D2A element, more details below. 

Here is technote on modeling D2A element, please go through it for its different applications. 

Modeling Reference - Discharge To Atmosphere 

Here is similar forum discussion on modeling pipe break for your reference. 

D2A Element for Pipe Breakage 

Information about modeling hydrant opening / closure in Hammer. 

Transient simulation for a hydrant closure or opening 

Hello Parsa, 

For both of this cases you can use discharge to atmosphere - D2A element, more details below. 

Here is technote on modeling D2A element, please go through it for its different applications. 

Modeling Reference - Discharge To Atmosphere 

Here is similar forum discussion on modeling pipe break for your reference. 

D2A Element for Pipe Breakage 

Information about modeling hydrant opening / closure in Hammer. 

Transient simulation for a hydrant closure or opening