<?php //Start loading a product resources $product = Mage::getModel('catalog/product')->load($productId); //save the product into the registry Mage::register('product', $product); //display $product's related products echo $this->getLayout()->createBlock('catalog/product_list_related')->setTemplate('catalog/product/list/related.phtml')->toHtml(); ?>
Refresh the page and now your related products will be display. Hope this will help to someone.