The left-arm spinner's victims included Kevin O'Brien (nine), who hammered the fastest century in World Cup history in his team's upset victory over England, as Ireland lost their last eight wickets for 85 runs.
Yuvraj (5-31) gave the capacity crowd plenty to cheer about after left-arm paceman Zaheer Khan had rocked Ireland with two early wickets. Zaheer finished with 3-30.
Porterfield (75), dropped on nought by Yusuf Pathan in the slips off Zaheer, went on to complete an impressive half-century, his fifth in one-dayers, before being caught in the covers off Yuvraj. He hit one six and six fours.
Ireland were on course to post a challenging total following a 113-run stand for the third wicket between Porterfield and Niall O'Brien (46) before they slipped from a healthy 122-2.
They suffered a crucial blow when well-set Niall O'Brien was run out after completing 1,000 runs in one-day internationals. His brother, Kevin, failed to repeat his heroics from the last match as he offered a return catch to Yuvraj.
There was no hint of the slide when Porterfield and Niall O'Brien were steadying the innings after Zaheer's double strike.
The Irish pair never looked in trouble, comfortably gathering runs against both pace and spin. They initially relied on singles and twos before Porterfield swung leg-spinner Piyush Chawla over square-leg for a six.
Zaheer earlier struck with the fourth delivery of the match when he bowled Paul Stirling for a duck before having Ed Joyce caught behind for four.
Earlier, India captain Mahindra Singh Dhoni won the toss and put Ireland who set a modest target of 208 runs for the hosts.
India are aiming to maintain their unbeaten run at the event after beating Bangladesh and tying with England, while Ireland are seeking their second win in three matches.
India retained the team which tied the last match against England at the same ground.
Ireland made one change from the side which shocked England by three wickets at the same venue on Wednesday, bringing in Andrew White in place of Gary Wilson.
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