Pāṇini sūtras

Before the affix ḍha (eya), the Vṛiddhi is substituted for the first vowel of the second member of pravāhaṇa but optionally so for the first vowel of the first member (i. e. pra)

1. pravāhaṇasyaप्रवाहणस्य

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   pप्	pravāhaṇaप्रवाहण	pravāhaṇasyaप्रवाहणस्य	pravāhaṇa [word]प्रवाहण [wओर्द्]	pravāhaṇप्रवाहण् + plus asyaअस्य

2. ḍheढे

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   ḍड्	ḍhaढ	ḍheढे	ḍhaढ	ḍhढ् + plus eए

Anuvṛtti

1. uttara+padasyaउत्तर+पदस्य 7·3·10

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   uउ	uttaraउत्तर	uttaraउत्तर	following	uttarउत्तर् + plus aअ
   pप्	padaपद	padasyaपदस्य	word	padपद् + plus asyaअस्य

2. vāवा 7·3·26

   Part	Lexeme	Sandhi form	Meaning	Stem
   vव्	vāवा	vāवा	optionally	vāवा