Smith, the British No 1 from Essex, was first to go, losing 7-6, 6-4 to third-seeded Lisa Raymond of the United States.
Ahl put up a strong fight but the experience of Dominique van Roost, the sixth seed, proved too much and the Belgian won 7-5, 6-2.
Smith went very close to pulling off a surprise when she had four set points in the first set and led 4-2 in the second, but Raymond, who reached the fourth round of the French Open, applied pressure at crucial times to clinch victory.
"Obviously I'm disappointed with the result but she played some unbelievable points and I couldn't have done anything more," Smith said. "When she had chances she was able to put big serves in. I wasn't able to raise my game when I needed it."
For Ahl it was the first experience of taking on a top-100 player. Van Roost was the world No 28 at the start of the week. The Devon player was pleased to find that her level - around the 200 mark - was not too far away from the higher standard.
"I didn't really know what to expect," she said. "I was pleased to go out there and compete with her."
It was also Ahl's first time competing in the main draw of a WTA Tour event. On Tuesday she won her first-round match 6-4, 6-4 against Claire Taylor of Oxford. "It's great to get through the first round and great to play players like Van Roost," she said.Reuse content