Showing product dimension at product meta

Hi i have this code at /single-product/meta.php

<?php
   $dimensions = $product->get_dimensions();
   if ( ! empty( $dimensions ) ) {
      echo '<div class="dimensions">Rozměry: ?.' . $product->get_width();
      echo ' h.' . $product->get_length();
      echo ' v.' . $product->get_height() . " " . get_option( 'woocommerce_dimension_unit' );
      echo '</div>';        
   }

?>

But it works only for single product. If i have product with variations it’s blank.

Also tried, this, but not work.

global $product
$variations = $product->get_available_variations();
foreach ( $variations as $variable_array ){
    $variation = new WC_Product( $variable_array['variation_id'] );
    echo "The length is {$variation->length}.";
}