this gist code use for move your carrirerwave file from assets s3 of amazon to you local file.

move-carrierwave-image-from-s3-to-local.rb

CarrierWave.configure do |config|
    config.storage = :fog
    config.fog_credentials = {
      provider: 'AWS',
      aws_access_key_id: ENV['AWS_ACCESS_KEY_ID'],
      aws_secret_access_key: ENV['AWS_SECRET_ACCESS_KEY'],
      region: ENV['FOG_REGION']
    }
    config.fog_directory = ENV['S3_BUCKET_NAME']
end

images = {}
Image.all.each do |image|
  images[image.id.to_s]=image.file.url
end

CarrierWave.configure do |config|
    config.storage = :file
end

Image.all.each do |image|
   image.remote_file_url=images[image.id.to_s]
   image.save
end