His poor domestic run led to his omission from Brazil's World Cup squad for Russia.
"I came back to Chelsea to stay," Luiz told reporters. "When I took my decision to come back here from Paris it was to win the Premier League and to do something again with Chelsea, so I am very happy here.
Luiz has featured in both of Chelsea's pre-season matches under Sarri, who has started his reign with victories over Inter Milan and Perth Glory.
"I love Sarri's philosophy," Luiz said. "We play high, with a lot of possession in a technical way. He's trying to help us every single day to learn quickly his philosophy.
"A new philosophy always takes time. But it also depends on us. If we're dedicated every day and doing things every single day in training, we're trying to learn quickly."
Chelsea will face league rivals Arsenal and French top-flight team Olympique Lyonnais in their remaining pre-season fixtures before their Community Shield match against Manchester City on Aug. 5.
The London outfit begin their league campaign against Huddersfield Town on Aug. 11.
(Reporting by Aditi Prakash in Bengaluru; editing by Sudipto Ganguly)
