[{"name":"Kartik","motos":[{"model":"A1"},{"model":"A3"}]},{"name":"Niharika","motos":[{"model":"A1"},{"model":"A2"}]}]

db.collection.aggregate([{"$set":{"motos":{"$filter":{"input":"$motos","cond":{"$in":[{"model":"$$this.model"},[{"model":"A1"},{"model":"A2"}]]}}}}}])