$filename = $file; //name of the file
$filepath = $file; //location of the file. I have put $file since your file is create on the same folder where this script is
header("Cache-control: private");
header("Content-type: application/force-download");
header("Content-transfer-encoding: binaryn");
header("Content-disposition: attachment; filename="$filename"");
header("Content-Length: ".filesize($filepath));
readfile($filepath);
exit;