Having chosen to bat first, Sri Lanka made 323 for 6, with Dimuth Karunaratne and Kusal Mendis making half-centuries, while the likes of Dhananjaya de Silva, Sadeera Samarawickrama, Dasun Shanaka and Wanindu Hasaranga also made valuable contributions.
The hosts then dismissed Afghanistan for 191, rounding off a clinical performance. Sri Lanka had lost the first match comfortably, on Friday, raising concerns that they might struggle in the forthcoming World Cup qualifiers in Zimbabwe.
"I'm very pleased with how we have bounced back," Silverwood said. "If you could bottle that performance and take it with you, you are going to be very consistent around the world. The key is to be consistent. They know they are capable of it now.
"We batted well and created partnerships. But equally, I thought, we were excellent in the field today. I saw lots of energy and lots of people supporting each other. We kept them below the [required] run rate and built pressure, and eventually it gave. We took wickets in the middle overs, which is something we needed today."
In addition to making 29 not out off 24 balls, de Silva also claimed the key wicket of Ibrahim Zadran, on his way to the game's best figures of 3 for 39. Although Afghanistan were behind the asking rate, de Silva's three wickets - which came in his three successive overs - helped send the opposition into a nosedive from which they would not recover. He had also hit 51 in the first ODI.
"I think in the first match he played a super innings," Silverwood said of de Silva. "Today we saw him go in and capitalise on what was a very good start. There was a great platform when he went in. He kept the momentum going and scored quickly. That's what we needed to get above that 300.
"When it comes to his bowling, he has been threatening to do this for a while. He's a very good one-day bowler. We saw that in Kandy last time we played Afghanistan there. Today, he bowled beautifully and got the rewards he deserves."
Sri Lanka's innings had been set up by the 82-run stand for the first wicket between Karunaratne and Pathum Nissanka, who made 43. Later, Samarawickrama and Mendis put on 88 together.
"I think Dimuth played superbly," Silverwood said. "He had played well in the Test series against Ireland as well. I think his tempo is very good, and I think between him and Pathum they built a great platform for us to build on. When you have an 80-plus opening stand, it always helps. They gave us that platform for the rest of the guys to spring from.
"The partnership between Sadeera and Kusal was a fraction over a run-a-ball and the partnerships after that were at more than a run-a-ball. It shows what we can do when we have wickets in hand and a platform. Pushing fielders into corners and making the boundary sweepers work very hard - it worked today."