The object of protection of design refers to "a new design based on the shape, pattern or combination of product and the combination of color and shape and pattern, which is aesthetic and suitable for industrial application", that is, the object of protection is the external shape characteristics of product, so its application documents only need to show pictures that can reflect the appearance. Note: the design does not protect the "functional structure", that is, it does not care whether the shape of the appearance is functional.
The object of protection of the utility model refers to "a new technical scheme proposed for the shape, structure or combination of products". In the case you described, the structure of the "groove" outside the bowl is a functional shape, which belongs to the protection object of the utility model. In the application document of utility model, not only the features of shape and structure should be described, but also the functions and corresponding technical effects realized by the shape and structure should be described in the specification.
To sum up, the shape of this bowl should be suitable for both design and utility model, and the protection scope of the two does not overlap. The design protects the "overall shape" that can be seen from the outside of the bowl, and a bowl similar to this "overall shape" may be suspected of infringement. The utility model patent protects the structure of putting chopsticks outside the bowl. If your patent agent can help you generalize this structure, it will protect many specific structures that can achieve this function, regardless of the shape of the bowl itself.